Johnson "70mod"

[hupiveneilija]

Here are couple of pictures for powerhead. I have also weighted rods and pistons, they are within .5grams the same. Crankshaft and flywheel are on the way.

[LittleCharger]

Are you going to blend the exhaust ports in the pic it looks like some mismatch still between block and sleeve.

will be interesting to see how those heads work. You may need head studs if the compression is real high as then tend to blow head gaskets without them

[hupiveneilija]

They are matched, picture may lie. I dont know what psi will be but head maker did it so that the compressionratio is aprx. 7.2:1, i think, with stock ex.port. Since I have raised the ports its lower now.
edit; I think he said that stock comp ratio was 5.9:1.

[filthy phill]

what is that metal wall behind the exhaust bridge ?
not seen this before, my block definitely dont have a wall behind the exhaust port.

did you put this there ?

[LittleCharger]

what is that metal wall behind the exhaust bridge ?
not seen this before, my block definitely dont have a wall behind the exhaust port.

did you put this there ?

Stock

[filthy phill]

what ?
are you saying this is normal for the 56 bridgeports to have this thick dividing wall in the exhaust behind the liner ?.

so this means the blocks used for bridgeports are not the same as oval port and sst60 motors.

[hupiveneilija]

Its the same lostfoam cast as sst60.

[filthy phill]

its is cast in the same way as SST60 yes, but it is NOT from the same casting as the 60/70hp fishing motor. they are different.
plus the sst60 also different height of block from top to bottom.. piston go over the top of the block on sst60. they do not go higher on normal block.
different casting numbers on the blocks too.

[Hevi Kevi]

its is cast in the same way as SST60 yes, but it is NOT from the same casting as the 60/70hp fishing motor. they are different.
plus the sst60 also different height of block from top to bottom.. piston go over the top of the block on sst60. they do not go higher on normal block.
different casting numbers on the blocks too.

Phillnjack - I mean Filthy Phill,
The reason the deck heights are different and pistons stick up past the deck is from people machining them to the minimum specs and using the longest allowable rods and cranks with maximum throw allowed. The bridgeport blocks are the same. Different sleeves. It's called a bridgeport because of the bridge in the middle of the exhaust port. The oval port is called an oval port because of the oval shaped exhaust port.

Kevin

[Hevi Kevi]

hupiveneilija,
Did you have any problems with the head warping when you welded up the chambers?

Kevin

[filthy phill]

con rods for sst60 are same as 70hp bridgeport. part number 394462 same length no different.
piston no for sst60 and 70hp bridgeport part no 394461 same pistons.
crankshaft for sst60 is what was used on 65, 70, 75 hp to 1986 (after that fishing motors went to multi spline) part number 328788 same throw 4 splines.

these are all omc specs and part numbers.

so no idea where the myth of the long rods and longer throw cranks come from.
I do know that is what fast fred would use in a special mod 50, but not what omc used for the sst60 motor.

[Hevi Kevi]

Yes, they are the same connecting rods and cranks. No, they are not all the same size. Everything has a tolerance. This is why guys pull apart piles of engines to build one.

[filthy phill]

not talking about guys trying to re-create a sst60 and building one up, were talking about a genuine OMC sst60 block being different to a fishing motor block.

[Hevi Kevi]

not talking about guys trying to re-create a sst60 and building one up, were talking about a genuine OMC sst60 block being different to a fishing motor block.

ok imagine this scenario
get a good 56 bridgeport fishing motor powerhead with say 130 psi compression. take of normal head and then put on a genuine un-molested sst60 cylinder head.
do you think this motor would even start let alone run good ?

It would start, run very well and likely be around 160psi

Kevin

[filthy phill]

would it realy
what about the large gap where the SST60 piston normally goes into the head.
Genuine sst60 head is not flat like the fishing motor head, it has a recess for the piston to enter.

I would of thought compression is going to be pretty low with this head on a fishing block thats NOT been decked to allow piston entry into the head.


.

[LittleCharger]

would it realy
what about the large gap where the SST60 piston normally goes into the head.
Genuine sst60 head is not flat like the fishing motor head, it has a recess for the piston to enter.

I would of thought compression is going to be pretty low with this head on a fishing block thats NOT been decked to allow piston entry into the head.




.

The piston doesn't go into the head on a decked block, it protrudes into the head gasket.

[filthy phill]

what ?
you saying that you could put a fishing motor head on a genuine sst60 and the piston would not hit the head ?

[LittleCharger]

what ?
you saying that you could put a fishing motor head on a genuine sst60 and the piston would not hit the head ?

Yup because the piston doesn't stick through the head gasket.

You need to look at the sst60 specs not sure where your getting the idea that the pocket width of the cylinder head is the diameter of the piston

[hupiveneilija]

hupiveneilija,
Did you have any problems with the head warping when you welded up the chambers?

Kevin

I really dont know, havent done myself, sorry.

I was wondering FastFreds "most positive trough" comment while ago, but then it opened to me😂. Toleranses. Thats why you need piles of motors as said.
I have worked with one I got, allthough I got one spare yesterday to play with if Ive done something really wrong, like transfer timing😊.

[hupiveneilija]

Some stuffing.

[filthy phill]

are these white plastic cards staying on
and what is that blue filler

[hupiveneilija]

Yes they stay, are between reedstops and frontpiece. Dont go anywhere.
Blue thing is marine epoxy. Same stuff on the crankcase.

[hupiveneilija]

What about egt meter for a tuning aid? Any help with that. And is there some target temp to aim or is it dependable for the mods i have made?

[filthy phill]

temp needs to be 140 ish if its too low its going to wear out fast. the 56 usually keeps good temp as long as good thermostat is in the motor.

DO NOT RUN WITHOUT THERMOSTAT.

[hupiveneilija]

Egt; ExhaustGasTemperature!

[LittleCharger]

Egt; ExhaustGasTemperature!

I'll quote Dave Bush on this one

"Pyros are a good reference tool

Yes and no. Most likely it will be dead before you see any temp changes even with fast pyros if bad detonation is happening. Temps usually drop a little then it dies. Sometimes you see a slow rise then the drop... Bottom line we have found when lake testing you have to take the time to do it the old fashion way and look at the piston tops and spark plugs period. A few minutes here saves thousands. Forget about the pyro. Pyro placement is a complicated thing in itself. Also, we have found you need a pyro in each cyl. with a fast hertz logging rate to do it right. If you can , do it,it is good info but it wont keep things from blowing up. Only you can. Or if you have det sensing you see it in real time (and if detonation is present) you simply let off the gas, change the fuel or timing and watch the rattle go away..We used to hurt alot of parts when living only by the Pyro. Now we look at it more for reference for cylinder to cylinder mapping. Hope that helps..... "

[hupiveneilija]

Thank You LC, just what I wanted to hear.

[filthy phill]

will you be putting finger ports in this motor ? if so how will you be doing that.

[hupiveneilija]

Things go forward. Just use grease to get those needles in place. Foto will show how ive grinded rods to be even. Use old pistons with new rings and honed the sylinders.

[filthy phill]

Was it a flex hone with small balls or 3 leg hone.
Are you sure the rods are still good at the crank end on the inside ? From pic looks like chrome has worn away.

[hupiveneilija]

Back together! Waiting for going back to the boat and startup. Have some work with the boat because transom has been done completely new and also have to blueprint the hull.

Has anybody tried those newer 70hp carbs with black plastic top? Are they worth nothing compairing to the older version?
Also went older pack with appropriate stator. Should be unlimited.
Really exited to see how it works, or dont😬.

[filthy phill]

Be interesting to see if it goes with that cylinder head, from the tiny size of combustion area it looks very strange .

have checked to see how many cc it is ? and what is the cranking compression now ?

will you run the engine on the stand for a while before putting on boat to run it in nice and slowly ?

[hupiveneilija]

That is the boat where the 70mod is going to.

[filthy phill]

that should be good for about 50 to 52mph with your mod engine. at around 6500 rpm with a good 23 pitch prop.

what make is the jack plate ? or did you make that yourself ?
i have never seen one the same as that before.. looks realy good.

the boat looks familiar, pretty sure i have seen these in the uk too, they look nice and sharp, plenty of rails so should be good in the rough stuff.

looks like its going to be a real good offshore racer, plus looks good even in the garage.

[zul8tr]

If you had a pad on that deep Vee it would run faster and be more stable (minimal lateral rocking) at speed. The right pad dimensions will reduce water drag. The pad would require a higher engine set since to do it would remove some of the bottom Vee.

Details here on why a pad:

http://www.aeromarineresearch.com/publications/RIB_jun2011.html

complete article available from Jim Russell see lower left of article.

[hupiveneilija]

If it is that slow, then i have to put stock motor back to the boat. It went 57.5mph with it.

[filthy phill]

if you got 57mph with the boat and motor why on earth have you stripped it down ?

what speed and rpm are you expecting to get from the boat motor combo ?
and what size prop ?

[hupiveneilija]

I dont know, for fun? Or maybe i want to try if i can make my motor rev higher and go faster. Go figure..

[filthy phill]

is the boat an Argo 16 or Argo 15 ?

[hupiveneilija]

Its 17. By the way, jackplate is Panther450.

[filthy phill]

ahh the Argo 17, i know these boats , they were around a long time ago, very nice boats,
the panther jack plate is nice and very expensive, certainly not under any pressure with just a 70hp motor.never seen one in the flesh.

[hupiveneilija]

Try to start 1st time after build, cranks really poor on my old battery even it was fully charged. Will need fresh good battery to start her up, i think have quite much compression😂. Havent measure yet. Have to get that new battery first and try again. If it dont crank enough then have to open those little holes in the cylinders.

[LittleCharger]

Try to start 1st time after build, cranks really poor on my old battery even it was fully charged. Will need fresh good battery to start her up, i think have quite much compression��. Havent measure yet. Have to get that new battery first and try again. If it dont crank enough then have to open those little holes in the cylinders.

it should crank even with high compression, like you said good battery and also a good starter, check for voltage drop at the battery to start and then work you way through, make sure you have good grounds

[LittleCharger]

looks awesome !

[filthy phill]

if that is the head on there with small combustion chambers you probably wont start it without 24 volts.
I would be doing compression check before starting it up.

[hupiveneilija]

it should crank even with high compression
And it did! Got second battery on the side, cranks verywell. Allthoug it didnt start, but I think have solved that. All wires from powerpack to the coils were in wrong order! Had to stop for tonight, getting late. New day tomorrow!

[hupiveneilija]

compression check before starting it up.
Fire up first then check 😬.

[filthy phill]

I do hope this runs good for you.
you have put a lot of work in the motor.

Be good to hear it run, I hope you have video ready for us to hear the beast running.

[Ron Hill]

Fire up first then check .

http://www.odysseybattery.com/battery_search.aspx?gclid=CJi-0K23jNQCFZ24wAodg6QHIw

These batteries worked GREAT on our 45 SS, amazing cranking power.

[filthy phill]

I use a banner 75amp with 660 cca. Works a treat.

[hupiveneilija]

Damaged propeller gets a new job. Cut the plades few cm, can use as a testprop on boatramp.

[hupiveneilija]

Here it is! https://youtu.be/oPcqyNwOrxE
Funny how much better it works when wires are in right places. Tomorrow to the boatramp with that "testprop" and see how it run.
1. 145psi 2. 148psi 3. 146psi. Cyl.head temp aprx.60*c. Ign timing 2*btdc.

[filthy phill]

it is running hooray.
sounds nice and crisp 2 stroke ..good.

not high compression though ? why seems very strange unless the head was from a 50hp 3 cylinder ????

[hupiveneilija]

it is running hooray.
sounds nice and crisp 2 stroke ..good.

not high compression though ? why seems very strange unless the head was from a 50hp 3 cylinder ????

Porting, ex timearea. With stock porting supposed to be higher. Correct?

[zul8tr]

Higher exhaust porting yields less static compression pressure because less cylinder volume from TDC to top of port. Most stock 2 cycle outboards are about 6.5 compression ratio (CR) relative to top of exhaust port, if you raise the exhaust ports that lowers the CR relative to exhaust.

[hupiveneilija]

Thats the case. And scavening & cylinder filling when running rpms is another, it might have quite high dynamic compression.

[zul8tr]

Yes much greater dynamic compression that cranking, engine is dealing with a hopefully controlled burning fuel air mix that expands rapidly and if ignition timing correct and other factors the max pressure on the piston will occur near 10-15 degrees ATDC to push it down. Depending on a lot of conditions dynamic pressures could exceed 800psi

[filthy phill]

Zul8tr
you said
"Higher exhaust porting yields less static compression pressure because less cylinder volume from TDC to top of port. Most stock 2 cycle outboards are about 6.5 compression ratio (CR) relative to top of exhaust port, if you raise the exhaust ports that lowers the CR relative to exhaust. "

to counteract the raising of the exhaust port (40 thou) many things have been modified.
The idle reliefs have been closed off ? this should raise compression.
the head being skimmed ? this should raise compression.
and the combustion chamber itself being reduced to about 2/3rds its normal size ? should dramatically raise compression on its own..
these 3 factors should of raised the compression to far exceed that of the OMC SST60.

I think another known to be reliable compression gauge would be a good idea to know what is realy going on, simply because 145 psi is not
even close to what is considered a high compression OMC 56.

I would of been expecting atleast 175 psi, then bed in and make around 180 to 190 psi .

[hupiveneilija]

Good morning!
Engine starts nice and idles like nothing with forward gear. My "testprop" is awfully heavy when buried down deep, had to lift so that a/v plate is level with water surface. Ign on idle 4*atdc, max 17* now. 800rpm with gear. That prop shakes alot. Better have official version. Reacts nicely to throttle input especially over 3k, instant 7k when smash the pedal😬. Picture for plugs after few minutes in 6000rpm, not wot, then shut.
Sorry no video, alone in a ramp.

Hope it works when on the move and gets plane.

[hupiveneilija]

Higher exhaust porting yields less static compression pressure because less cylinder volume from TDC to top of port. Most stock 2 cycle outboards are about 6.5 compression ratio (CR) relative to top of exhaust port, if you raise the exhaust ports that lowers the CR relative to exhaust.
This is 5.9 stock and with that small chamber head 7.2 BUT with stock porting!

[zul8tr]

Zul8tr
you said
"Higher exhaust porting yields less static compression pressure because less cylinder volume from TDC to top of port. Most stock 2 cycle outboards are about 6.5 compression ratio (CR) relative to top of exhaust port, if you raise the exhaust ports that lowers the CR relative to exhaust. "

to counteract the raising of the exhaust port (40 thou) many things have been modified.
The idle reliefs have been closed off ? this should raise compression.
the head being skimmed ? this should raise compression.
and the combustion chamber itself being reduced to about 2/3rds its normal size ? should dramatically raise compression on its own..
these 3 factors should of raised the compression to far exceed that of the OMC SST60.

I think another known to be reliable compression gauge would be a good idea to know what is realy going on, simply because 145 psi is not
even close to what is considered a high compression OMC 56.

I would of been expecting atleast 175 psi, then bed in and make around 180 to 190 psi .

In my statement I was referring to a relative change in pressure with previously all else remaining the same. You are correct other things were changed so why the low psi? What was the compression pressure before all mods?

Not being familiar with your engine internals not sure how idle reliefs would affect compression psi.
Yes on head work to increase compression psi.

Redo the compression test with the cylinders oiled up to better seal the rings. If great difference the rings leak a lot, if not it is what it is by that gage.

Do a leak down test.

Yes possibly a different compression gage would give higher psi? Regardless because different gages will read different. I only use Bourdon mechanism type gages for relative differences in psi rather than absolute pressure psi and I always use the same gage to preserve the accuracy of relative psi measurement differences. Bourdon type gages are simple diaphragm expanding mechanisms that are calibrated to a standard using a dead weight tester or other accurate reference testers. Unless calibrated you will find differences among gages since you will not know the past history of the gage treatment and even new identical gages will read different.

[filthy phill]

I just looked at the picture of the spark plugs, why the thick copper washers ?

[filthy phill]

did you balance your testing prop ?
I had a prop that was terrible for vibration, once I balanced it there was no more problem.

but I also have a prop that when balanced is still crazy for vibration..

[hupiveneilija]

https://youtu.be/XZ6xrDQQnxw
Is this fourstrouking? Seems like there is pretty much unburnt mixture coming from exhaust. So something has changed😂. Hesitates in lower rpms like i think cause by overrich mixture. And then there is that stock tuner wich propably makes it feel kind of "liveless" on high rpms. That vibration i mensioned with "testprop" , its the engine itself.
Ignplugs threads are that much shorter now on the head.

https://youtu.be/mYgMwxCKJE8
Too much primarycomp might cause that unburnt mix going through engine?
HAH, my tach dont show over 7k, needle dont know what to do!😂

[hupiveneilija]

Took away stuffing i made around reeds, dont push mix to the exhaust on idle anymore. Those plugs i made for comp relief holes, same stuff as nosecone, are gone. Infact i think they were gone by the time i made comp test. Maybe thread and little setscrew. Went out today, ran 45.5kn with 18 raker, dont know revs cause needle stops little over 7k. Have some water issue, dont idle good on water or flushhose. Without better, might be headgasket. Is there a chance that headgasket blows with too much waterpressure? Little lazy for going on plane under 3k especially with raker, dont slip enough, but when nose go down then it goes. Feel like needs to start playing with tuner. But before that i try with srx how it works.

Sorry for tight typing😊

[filthy phill]

No it is not too much compression.

you are not firing on all 3 cylinders all the time. there is no crisp 2 stroke sound.
before on your older video showing boat going fast your engine sounded very crisp , very good.

what oil and fuel are you using now .
what are the plugs ? Champion QL77JC4 ? or Champion QL78YC .

you will always get some 2 stroke oil in the water from the exhaust, that is normal.

[filthy phill]

with 18 raker it should fly from zero. 18 is small for that motor . maybe need 12 to 13 mm vent holes, omc vents are too small.

have you tried with plugs and no copper washer ? it will let the spark be in the correct place to fire.

I also asked lots of people about the tuner to make it shorter, but everyone who is expert on tuners say you will lose bottom end power on v hull.
short tuner just for very light tunnel hulls. ?

[hupiveneilija]

No it is not too much compression.

you are not firing on all 3 cylinders all the time. there is no crisp 2 stroke sound.
before on your older video showing boat going fast your engine sounded very crisp , very good.

what oil and fuel are you using now .
what are the plugs ? Champion QL77JC4 ? or Champion QL78YC .

you will always get some 2 stroke oil in the water from the exhaust, that is normal.

It might run little better with QL78YC, tried both. Yes i know there is always oil in exgases but it was like pouring through before took stuffing out. It may have weakened lower end a little bit.

Think that transfer timing is too much, causing that lame lower rpm behavior

I run our 98e5 with some fully synthetic oil ment for bikes.

[filthy phill]

have you tried with extra spark plug washers taken off ?

[hupiveneilija]

Those plugs i made for comp relief holes, same stuff as nosecone, are gone. Have some water issue, dont idle good on water or flushhose. Without better, might be headgasket. Is there a chance that headgasket blows with too much waterpressure?

Ordered J-B Weld HighHeat epoxy putty for relief holes and solved the water issue; What a dumbass I am, forgot to retighten the head bolts so they werent tight enough and water went to cylinder(s) and gasket was also broken between thermostat and #1. :o

I bet it run better after fixing those.

Good night everybody!:)

[filthy phill]

ha ha we all forget the simple things. the hard things we all remember, bu the re-torque the main head bolts we forget about .
glad you have found your water problem, you will be fine soon

[LittleCharger]

Ordered J-B Weld HighHeat epoxy putty for relief holes and solved the water issue; What a dumbass I am, forgot to retighten the head bolts so they werent tight enough and water went to cylinder(s) and gasket was also broken between thermostat and #1. :o

I bet it run better after fixing those

Good night everybody!:)

Keep an eye on the head gasket a tight head like that tends to blow them, head studs help

[hupiveneilija]

Ill do that, thanks!
Have to find studs & nuts somewhere.

BTW Good Morning! :cool:

[LittleCharger]

Ill do that, thanks!
Have to find studs & nuts somewhere.

BTW Good Morning! :cool:

What size of main jet are you starting with?

[hupiveneilija]

I have original mainjet now, dont remember what it is in those carbs. Made 1 WOT and shutdown, plugs look ok. Pulled head off last night, pistons seems like ok to me.
Have to do those reliefholes with J-B and assemble the head back, then can go out and drive more so that i can see how pistons look by the transferports.

Must get tachmeter wich shows to 8000.

Ouh yes, I replaced those reedbodies, wich Ive stuffed all around, with stock ones. It felt like fighting against itself in high rpms. Better now but weakened lower end, have to find that sweet middle.
And stock tuner in Place, still revs like hell with 18in prop.
There is some tuning to make.

Btw is it any good to use coppergasket spray with headgasket?

[hupiveneilija]

This is how pistons look. #1 is clean because of water.

[Roflhat]

Cool build :cool:

[filthy phill]

why not put a slightly bigger prop on and save it revving to the moon, there is no point revving the nuts out of it with a 18 pitch.
you were running the 23 before the work, you wont know if its any stronger until you try that prop on it.

How many hours run are on it now since new rings put in ? 3 , 5 ?

[hupiveneilija]

I will put 23 next time I go out. Its got only max 2h. Have to wait that J-B so it takes few days.
What a luck, we have 1 company here that sells it.

[filthy phill]

not sure even the jb weld will hold up.
if it is nice and smooth in the holes you have no chance of it staying there. needs to be rough inside the holes
I think maybe alloy welding is the best way, then the sleeves dont get a chance to warp with steel welding.

hope the jb weld does work, makes it a real easy job.

[skeg]

Ill do that, thanks!
Have to find studs & nuts somewhere.

BTW Good Morning! :cool:
If you find someone that make heads studs please post it

[LittleCharger]

I have original mainjet now, dont remember what it is in those carbs. Made 1 WOT and shutdown, plugs look ok. Pulled head off last night, pistons seems like ok to me.
Have to do those reliefholes with J-B and assemble the head back, then can go out and drive more so that i can see how pistons look by the transferports.

Must get tachmeter wich shows to 8000.

Ouh yes, I replaced those reedbodies, wich Ive stuffed all around, with stock ones. It felt like fighting against itself in high rpms. Better now but weakened lower end, have to find that sweet middle.
And stock tuner in Place, still revs like hell with 18in prop.
There is some tuning to make.

Btw is it any good to use coppergasket spray with headgasket?

I would fatten your main jet if you have raised your ports and bumped the compression, as soon as you load that motor with the bigger pitch prop she is gonna melt the exhaust side out. Main jetting for sst60 spec motors is generally 72 and 73 your probably like a 65. You want to go fat and work your way down not a lot of clean wash on those pistons it does show some but that could be lower rpm wash.

Fuel is power if you haven't increased your jetting to flow more fuel your either gonna burn it up or you haven't really made any increases in noticeable power (ie. factory jetting is usually a little fat)

[hupiveneilija]

I would fatten your main jet if you have raised your ports and bumped the compression, as soon as you load that motor with the bigger pitch prop she is gonna melt the exhaust side out. Main jetting for sst60 spec motors is generally 72 and 73 your probably like a 65. You want to go fat and work your way down not a lot of clean wash on those pistons it does show some but that could be lower rpm wash.

Fuel is power if you haven't increased your jetting to flow more fuel your either gonna burn it up or you haven't really made any increases in noticeable power (ie. factory jetting is usually a little fat)
In my carbs, wich are from 1992model as my engine, they are 50. There are so many variations of these carbs and every single one have different jetting.
How much You think I go first up from stock? If I go 60 its 20% more. Too much?

[LittleCharger]

In my carbs, wich are from 1992model as my engine, they are 50. There are so many variations of these carbs and every single one have different jetting.
How much You think I go first up from stock? If I go 60 its 20% more. Too much?

60 will most likely be too much as that's more like a 37% increase in area, but I would rather go more then needed and start making some jetting passes and work your way down. I prefer reading piston wash over plugs, if you are going to read plugs you need to make sure you are looking at the base of the plug for reading, using one method to confirm the other is the best

[hupiveneilija]

Ok. If I have something like 55 I go with that or make one for those I got. If you think 60 is too much. I have plenty of carbs in a box! Also have three carbs from 2cyl, they are bigger than 70 ones. Maybe try one day.
Actually I have tried those before with old boat, it felt kind of a stronger for take off but made bowls empty after 3500rpm. I think that pump doesnt made enough then.

[sharpeye Mike]

It's funny how in 1989 they had two sets of carbs, the early sets had 65s and the later ones had 52s in them and in the early 90s they went to 50s. I just learnt something. I wonder if you would benefit from a set of older carbs. :confused:

[LittleCharger]

Ok. If I have something like 55 I go with that or make one for those I got. If you think 60 is too much. I have plenty of carbs in a box! Also have three carbs from 2cyl, they are bigger than 70 ones. Maybe try one day.
Actually I have tried those before with old boat, it felt kind of a stronger for take off but made bowls empty after 3500rpm. I think that pump doesnt made enough then.

the Bridgeport 70hp 56er carb has the same venturi size as the two cylinder. Are your carbs form the 56er 60hp motor?

[hupiveneilija]

No they arent, from 1992 70hp. I think biggest 3cyl carb. I have three sets of 60hp carbs, way smaller. Those three even bigger than 70 I think they are from 2cyl 60hp.
Ive got all 3 model of 70 plus later blacktops.

[hupiveneilija]

It's funny how in 1989 they had two sets of carbs, the early sets had 65s and the later ones had 52s in them and in the early 90s they went to 50s. I just learnt something. I wonder if you would benefit from a set of older carbs. :confused:
Yes and thoseearly 65 dont have idle jet at all, dont have even hole for that. 52s have idle jet, or viceversa dont remember wich way😂. Then there is middle jet, some have for fuel, some for air. Fuel version have screw front of it. And this new version with idle screw. And ovalport blacktops with idle screw and 2 jets.

Tube from bowl to venturi different in all carbs.

Older with chokeflaps. Somewhere like -83 and on primerchoke.
Very confusing.

[LittleCharger]

No they arent, from 1992 70hp. I think biggest 3cyl carb. I have three sets of 60hp carbs, way smaller. Those three even bigger than 70 I think they are from 2cyl 60hp.
Ive got all 3 model of 70 plus later blacktops.

2 cylinder 60hp carbs are same venturi as the 1992 70hp

[hupiveneilija]

Have another problem now.#1 stuck like it was before when I opened PH. Think it has to be something with cooling. And salt&water, no good. Might put another PH on place.

If it have 2 stock pistons and middle .020 over should I jet it different?

But hey, atleast older electronics work! No rev limiter😂. Think I put that head to stock PH as planned originally and see how it works. Have to get some driving hours for setting the boat as good as it can be.
Maybe a little chamfer on the export😬.

Cant load pictures.

[filthy phill]

when I tell people there are bigger carbs out there they dont believe me.
.

[filthy phill]

you probably have the same problem because the bore was scored from the last piston damage.
you honed it, but could still see the score lines from your pictures, and if its number one then yes maybe a water problem.
have you taken the exhaust cover off and made sure the hole in the top is free into the water jacket ? its a small hole about 3mm up in the very top.

some of the early 56 motors did not have good water cooling and there was a service bulletin about it, dont remember the number of the bulletin, but here is a diagram I
got sent to me showing about a water modification to the 56 motors pre 1986 to 1994, showing where some need to be drilled .
maybe someone on here knows a bit more about this.

I think this was mainly due to number 1 (top) and number 2 getting the pistons scored up ? maybe a proper OMC guru can help more with this bulletin.

ALSO there is a bulletin about changing the thermostat and cover, and the exhaust cover plate due to bad cooling..
The improved exhaust side cover plate part number is 343864 also needs the correct gasket to fit this.
ALSO there is the service bulletin about the water pomp and thermostat.
pics below

maybe these need to be done on your motor, you are definitely running early thermostat housing.

hope it helps
.


.

[LittleCharger]

Have another problem now.#1 stuck like it was before when I opened PH. Think it has to be something with cooling. And salt&water, no good. Might put another PH on place.

If it have 2 stock pistons and middle .020 over should I jet it different?

But hey, atleast older electronics work! No rev limiter😂. Think I put that head to stock PH as planned originally and see how it works. Have to get some driving hours for setting the boat as good as it can be.
Maybe a little chamfer on the export😬.

Cant load pictures.

Did you blow another head gasket?

Regardless of the piston size you jet each cylinder on it's own.

Are those needle bearings dirty or on their last leg lol

[filthy phill]

they look like the original old roller bearings to me, and that piston has been sanded down to get old score marks off it.
I am also wondering if any little metal particles are still floating around in the block after port work.

[hupiveneilija]

Did you blow another head gasket?

Regardless of the piston size you jet each cylinder on it's own.

Are those needle bearings dirty or on their last leg lol

No I didnt. Was on its way to seize like before. Ive used this engine around 5 summers and when opened head in the winter it was also like that. I think its cooling related.

Those bearing are little dark because of that gasket/water problem. Havent disassembled ph yet to see how bad crankshaft bearing is. Dont know if I can use those.
Sad I dont have any used .030 piston, that one is gone now I think.

Ive got 2 extra powerheads, one with that oversize piston and one allmost like new inside wich I dont like to use for now.

Have disassemble that oversize one and clean up then put together and running. Must solve cooling issues too.

[hupiveneilija]

you probably have the same problem because the bore was scored from the last piston damage.
you honed it, but could still see the score lines from your pictures, and if its number one then yes maybe a water problem.
have you taken the exhaust cover off and made sure the hole in the top is free into the water jacket ? its a small hole about 3mm up in the very top.

some of the early 56 motors did not have good water cooling and there was a service bulletin about it, dont remember the number of the bulletin, but here is a diagram I
got sent to me showing about a water modification to the 56 motors pre 1986 to 1994, showing where some need to be drilled .
maybe someone on here knows a bit more about this.

I think this was mainly due to number 1 (top) and number 2 getting the pistons scored up ? maybe a proper OMC guru can help more with this bulletin.

ALSO there is a bulletin about changing the thermostat and cover, and the exhaust cover plate due to bad cooling..
The improved exhaust side cover plate part number is 343864 also needs the correct gasket to fit this.
ALSO there is the service bulletin about the water pomp and thermostat.
pics below

maybe these need to be done on your motor, you are definitely running early thermostat housing.

hope it helps
.


.
That 5/16 hole, where does it go if drilled?

[hupiveneilija]

That 5/16 hole, where does it go if drilled?

It goes behind the exhaust cavity and there to middle wall cylinder side.

[filthy phill]

the hole that gets drilled goes into water cavity between cylinder and block. it would be there to make sure water gets in and not just trapping air.

this modification was later improved on even more, by putting the hole up even higher inside the exhaust cavity.

I will take some good quality pictures today of the hole on my later model to show you where it is best to be for the cooling...

because on the later oval port motor the hole is right up the top in the corner.
I will take pictures of it later today for you, I checked it out recently on a old spare block I have same as mine.
it is there so no air gets trapped and lets exhaust side of the pistons correctly.
on the 1994 onwards all this is done at the factory to solve all the cooling issues.
if you put a torch into the top toy can see light at the side, and if torch at the side you see light between cylinder sleeve and the block.

also the large exhaust plate gets later one to also improve the water flow/cooling and must be fitted with the new gasket also.

I have got to get to my garage to move a few items and the engine block is at front, so will definitely take pics and post them for you.

there is lots of service bulletins , but nobody seems to share them enough on the internet..

would of been nice if someone put up lots of bulletins for people to see.

[hupiveneilija]

Done this. IMO has to be enough flow but there is not.
But how much pressure is too much? Where is that pressure relief ment to be to flow past thermo? If I make pressure relief lower by softer spring or some kind of a bypass hole next to thermo?

[filthy phill]

what is the exact model number of the engine ?

•Model . J70TLCCA =1988 ..........J70TLCCA = 1989.............J70PLEEE = 1990 ..........J70TLEIE =1991..........J70TLCCA = 1992.

[filthy phill]

here is a couple of pics to show what OMC done to inside the exhaust cover to improve the cooling of the no 1 and 2 cylinders.
the small hole at the top lets plenty of water get to the top two culinders and any air expelled out the top tell tale fitting on the top of the block.
this simple mod made a lot of difference.
along with changing the timing to 17 deg instead of 19.. seems 19 made it run too hot ? also larger main jets were put in the carbs to stop the motors leaning
out and destroying the pistons and sleeves.

anyway, here is what OMC done to make the later oval port run the best for cooling.

[hupiveneilija]

Its 60tlene. I made that 5/16 hole and all holes from ex cavity side to cylinders little bigger, including that little hole on up. Also made that upper corner on divider wall larger. IMO water must flow.

[hupiveneilija]

Here is more todays achievements. Now like it was ment to be in first time😂😂. Only cleanup and 45* angle on ex ports.

[filthy phill]

so your engine with this number is a 1992 johnson 60hp, this had the small carburettors with the 1.25 venturi.
this model needs the updated water pump and updated exhaust cover and updated thermostat and spring and cover.
it also needs the updated water pump and the stainless plate below the water pump updated. they are different plates and different impellors.
with these improvements and 17deg timing you should not get over heat problems. with everything be normal ..
unless there is problems with the piston clearances, too much will cause piston slap, too little will cause overheat of the metal and scoring obviously.

with all the work your doing it is very important to get plenty of water THROUGH the motor.

Now back to your engine, running at 7,000 rpm plus you need plenty of water to go through the motor, maybe your idea's will let more through,i really dont know.
maybe someone else on here like fast fred can advise on exactly what you need to be doing.

If it was me I would definitely get the improved thermostat and housing and spring so the pressure reliefs let the water through correctly..
you might lose a bit of pressure, but your pressure is pretty high anyway.

did anything happen to any of the bearings when it got hot ? or seals.

.

[hupiveneilija]

Question, wich reeds? CCMS or Boyesen?
CCMS use original stopper plate, Boyesen dont. If boyesen is it okay to use stopper plate with those? They say ditch them. Think that leaving those off would lower cc pressure little bit. Any matter?
What do You prefer?

Did some head volume measurement today. Plug in place.
329835-1 34cc
329835-4 32cc
336306-4 30cc
70mod 21cc

[hupiveneilija]

with all the work your doing it is very important to get plenty of water THROUGH the motor.



If it was me I would definitely get the improved thermostat and housing and spring so the pressure reliefs let the water through correctly..
you might lose a bit of pressure, but your pressure is pretty high anyway.

.
Pressure may drop, have to get flow and volume yes.

[filthy phill]

so your now using another powerhead to modify ?

[hupiveneilija]

Yes , because I dont have .030 useable piston for white ph. Well I do have new set some wisecos and bored ph. Dont want to use it now. Saddly someone has has done some cleanup for it and made same error as I did, moved transfers up when smoothening them.
Havent measure how much.

Make this thing go without seizeng first.

DEVCON has some epoxyputty wich I try for transfer roofs.

Btw June 1st, outside temp 4*c no rush to the sea!

[LittleCharger]

Yes , because I dont have .030 useable piston for white ph. Well I do have new set some wisecos and bored ph. Dont want to use it now. Saddly someone has has done some cleanup for it and made same error as I did, moved transfers up when smoothening them.
Havent measure how much.

Make this thing go without seizeng first.

DEVCON has some epoxyputty wich I try for transfer roofs.

Btw June 1st, outside temp 4*c no rush to the sea!

Yes you really need to understand what your doing when moving the transfers, a good block becomes scrap pretty quick. Generally just clean up on transfers. We use to turn in the 7's with a stock ported 56er with 160lbs compression with a nitro case and a 23 no problem, doesn't get much simpler then that.

Sounds like swimming weather at 4 degrees. We don't run a thermostat after break in but have to monitor heat in the block when testing in the spring due to cold water.

[hupiveneilija]

Yes you really need to understand what your doing when moving the transfers, a good block becomes scrap pretty quick. Generally just clean up on transfers. We use to turn in the 7's with a stock ported 56er with 160lbs compression with a nitro case and a 23 no problem, doesn't get much simpler then that.

Sounds like swimming weather at 4 degrees. We don't run a thermostat after break in but have to monitor heat in the block when testing in the spring due to cold water.

Thats true with transfers.

Do You leave therm/reliefvalve all away? I opened that plastic core and took thermo element&spring out. Center portion flows now all the time and then have to find/make softer spring for the valve.
Made those watercavity mods You see in a last photo . Those and this thermostat mod see how it works. Hope it flows enough.

But wich reeds? Ccms or Boyesen? Have both.

7*c YES! Its summer!

[hupiveneilija]

Putting powerhead together, degreed ex dur 180* and blowdown 29*

[filthy phill]

go and buy a new thermostat and the right spring and the new style cover. or you WILL destroy that motor.

if the 56 is not at right temp she will die very quickly.
do it right or you will be needing another block too.
Even fast fred always says about getting the 56 upto temp before hitting the throttle, with no thermostat you wont reach correct temp in cool water. if in Miami then yes, in finland NO.
with the right thermostat the motor will come upto temp in about 3 minutes maybe less.
I start my motor up and by the time I have released the ropes and lit a cigarette she is ready to put into gear, another 30 second and the temp is perfect, then it stays good.
even running full throttle I still keep around 60c degree in the winter, 65c in summer at 6300 rpm and heavy load. and will idle in gear all day at 70 deg c...

you need minimum 50c deg to run without being too cold for the engine, ideal is about 60c to 65c deg on max speed.

running too cold is just as bad as too hot ..

56 is not good if its too cold, the clearances are not correct and boom, another engine block for the junk pile.

leave the transfer ports normal and the boost, just raise the exhaust only.
you dont know and understand 2 stroke enough, your allways thinking 4 stroke technology.

get the normal head and shave 1.5mm then just put it on, then put it on and go play at 7500 rpm and hopefully she will last a little bit longer.
if you run at 8,000 then 20 hours maybe 30 if very lucky before needing re-build AGAIN.

on my project engine I will only raise the oval port and shave the head, everything else will stay the same, including timing and the electrics. but I only want 6500 to 6800 rpm and engine to last long time.
parts in the uk are very expensive, and I only use for fun not

[hupiveneilija]

improved thermostat and housing and spring .

.
What do You think is improved spring?

[filthy phill]

it is a totally different rate of spring and just different type, different thermostat and also different housing.
I have 2 styles of thermostat housing that are newer than yours, you cannot use the same spring in each housing cover, one is a cone shape and the other normal shape.
But both are very different to what your housing takes.
a pic below shows the thermostat cover is a very different shape to yours, its goes in not outward.

if you look at the later style you will see that the cover is almost flat with the centre slightly going in, your cover comes out by a fair amount.
if your going to be taking thermostats apart there is no point at all to even have one in there, then you can happily wait for the engine to destroy itself due to running too cold.
too cold means the wear on the motor is going to happen fast, very fast.

most people that run without thermostats are racers who have to re-build their motors in very short amount of running times anyway.
if your prepared to keep destroying stuff then just dont fit the right thermostat and housing and newer water pump, let it stay the same as it is.
the scoring of the top and middle pistons and sleeves was why omc sent out the bulletin, it happened to thousands of engines not just the odd one.
Joe reeves even speaks about the problem and I think it is on this very forum..


here below is 2 very different thermostat covers, and both of these are much later style than what you have. the springs will not inter change on these covers
take a close look you will see the centres are very different !!! 1 has a centre with 3 small prongs the other has 4, .
also a pic showing the complete breakdown of the parts.
it is very different to the older versions. this is what omc service bulletin recommended to keep the motors at correct temperature.

[filthy phill]

it is totally different to your thermostat spring .
it is also the housing that is different, not just the spring, it is the complete unit.
There is a large spring, small spring , thermostat, plastic housing , seal and the gasket and metal ring and poppet type thing, its complete different to older style..
here are some pics to show everything.

1st pic , notice the thermostat cover goes inward not out !!

2nd pic, two much later types of thermostat covers and springs, not interchangeable.

3rd pic, the breakdown of the complete thermostat assembly... very different to your older style thermostat assembly.

.

[hupiveneilija]

Went to testdrive today not white ph but with blue one. Made my speed record dont know what the engine rpm was but it was HIGH!

Made spacer between thermostat cover and head , then softened reliefvalve spring as much as I could. With these and those drillings&grindings done to waterjacket, pressure is now at full speed around 0,9to1,2bar. Engine warms up pretty fast but there might be just too much flow at speed.
Maybe put unmodified relief spring its place. After slowing down from wot head is aprox. 45*c from surface, could be higher.

To LC: I put 56 jets and middle is 57. Plugs shown in picture.
It feels really strong through hole revrange when on plane. And goes to plane with no drama.

I have stock tuner on it but still it revs higher than I imagined. Went 56.4kn 2.42 gears and srx my own desing. Dont know max rpm because tachmeter stops at 7000.

[filthy phill]

PLugs look perfect to me, propertan colour not lean and not too rich. ( but I am not an expert at reading plugs)
on temperature I would seriously get the new complete kit and be safe. 45 deg is far too cold.
your speed is fantastic. glad it s going so well for you. 56.4 knots is 65mph !!!! that is very fast on that boat and very fast on any boat :cool:

did this motor have new rings ? or just the exhaust ports modified. and exhaust water passages ?

[hupiveneilija]

Old used rings and pistons. Oh and ig timing 17*. Think that head did the trick. Fellow who did it knows his business!

[filthy phill]

what is compression, cold cranking all 3 plugs out and NO oil put in the bores, cannot get proper reading if putting oil down the bores.

[hupiveneilija]

Dont know, meter is at work. But must be low because it works so good:rolleyes:.
Did math and it gave 7.2 cr. From the point ex chamfer closes.

[filthy phill]

will be interesting finding out what the rpm is and the cold cranking compression psi..
but so far it seems as though its a very powerful motor.

[zul8tr]

what is compression, cold cranking all 3 plugs out and NO oil put in the bores, cannot get proper reading if putting oil down the bores.

And throttle full open.

[hupiveneilija]

And throttle full open.

Always;)

Installing new tachmeter so dont have to guess how much over.

[filthy phill]

throttle open or closed dont make any difference at cranking speeds, air comes straight back in from exhaust anyway.
ive often measured compression with and without fully opening the carbs and it dont make any difference.
I have even put a plate over the intake to seal it just to see what happened, no difference at all.. there is no explosing sending hot exhaust out in a hurry.
and obviously no one way vale closing the exhaust port, so it realy dont make a difference.
but do it what ever way you want, as long as you get the reading with it cold with no oil or fuel dumped in the bore to give a false reading.

on a 3 cylinder I always double check if its been left a while, but with this just having the pistons and rings out it will not be any sticky rings.

but be good to see how high or low it is.

and to see how high the rpm is , then can get an idea of how long the motor will last..

[LittleCharger]

62152

[filthy phill]

I see its 190 psi, but what motor is this on ?
is this a modified 56 omc ? how much taken off the head ? 80 thou ?

[LittleCharger]

I see its 190 psi, but what motor is this on ?
is this a modified 56 omc ? how much taken off the head ? 80 thou ?

Bridgeport, combination of things not just head, stock heads vary a lot any where from 30.5cc to 34.5 cc, some commercial heads are 42 cc, so it just depends on the head

[hupiveneilija]

62152
I have same meter now. It must be faulty because it shows way much lower numbers;). 145, 146, 135.

[hupiveneilija]

Bridgeport, combination of things not just head, stock heads vary a lot any where from 30.5cc to 34.5 cc, some commercial heads are 42 cc, so it just depends on the head
I measured also heads from 30 to 34 and my small chamber 21.
That 190, is ex port in stock timing? I have chamfer, 1.382 from deck.

My motor feels real good when running even its quite worn. White one when bored and built with new pistons 5 years ago wasnt nothing like this now. Think that crank psi isnt the hole truth as you go on higher rews. Big part of the story is scavening and how it works.
I think Ill try little more ign timing when go out next time. A degree or two. IMO my previus PH wasnt up to task, not even if I had limiter taken away, because it was just under that and was hitting occasionally.

[LittleCharger]

I measured also heads from 30 to 34 and my small chamber 21.
That 190, is ex port in stock timing? I have chamfer, 1.382 from deck.

My motor feels real good when running even its quite worn. White one when bored and built with new pistons 5 years ago wasnt nothing like this now. Think that crank psi isnt the hole truth as you go on higher rews. Big part of the story is scavening and how it works.

I think Ill try little more ign timing when go out next time. A degree or two. IMO my previus PH wasnt up to task, not even if I had limiter taken away, because it was just under that and was hitting occasionally.

Be careful on the timing, the 56er typically does not like more timing, if your looking for top end you don't want more timing

[hupiveneilija]

Okay, thanks! Maybe I leave it 17* where it is now.
If I get more prop somewhere then perhaps with lower rpms.

Think I concentrate on cooling to adjust it little warmer on speed but not much. Reliefvalve spring needs slightly more tension so pressure goes up a bit and flow little less water through block.

Btw looked inside of a plughole and there seems to be pretty much flowmark on piston, so it is on a rich side wich is good.

[zul8tr]

throttle open or closed dont make any difference at cranking speeds, air comes straight back in from exhaust anyway.
ive often measured compression with and without fully opening the carbs and it dont make any difference.
I have even put a plate over the intake to seal it just to see what happened, no difference at all.. there is no explosing sending hot exhaust out in a hurry.
and obviously no one way vale closing the exhaust port, so it realy dont make a difference.
but do it what ever way you want, as long as you get the reading with it cold with no oil or fuel dumped in the bore to give a false reading.

on a 3 cylinder I always double check if its been left a while, but with this just having the pistons and rings out it will not be any sticky rings.

but be good to see how high or low it is.

and to see how high the rpm is , then can get an idea of how long the motor will last..

Probably so for max pressure for electric start engines but I like to see and record all rope overs (no electric starter on my jobs) to judge how pressure builds especially 1st pull and full open matters here and is they way I do it to keep consistent results.

[LittleCharger]

Okay, thanks! Maybe I leave it 17* where it is now.
If I get more prop somewhere then perhaps with lower rpms.

Think I concentrate on cooling to adjust it little warmer on speed but not much. Reliefvalve spring needs slightly more tension so pressure goes up a bit and flow little less water through block.

Btw looked inside of a plughole and there seems to be pretty much flowmark on piston, so it is on a rich side wich is good.

Forgot your were at 17 you could go back up to 19, just wouldn't add any timing past that.

Fat is good til you get everything else dialed in then you can work on jetting

[hupiveneilija]

Forgot your were at 17 you could go back up to 19, just wouldn't add any timing past that.

Fat is good til you get everything else dialed in then you can work on jetting

I thought so also that 19* isnt too much, might be better down low for going on plane. I dont touch jetting at all for now. Maybe little fatter for middle jet is what to do.

[LittleCharger]

I thought so also that 19* isnt too much, might be better down low for going on plane. I dont touch jetting at all for now. Maybe little fatter for middle jet is what to do.

raising timing to 19 would help bottom end

[filthy phill]

I think the low compression is simply because the chambers have been made far too deep.
to be 21cc and made deeper they must be tiny diameter
just shaving the normal heads raises the compression, but making the cups deeper seems a bit strange for someone wanting top end speed and power.


the chamfer on the exhaust ports is correct, everyone puts chamfer on the top of the ports.

what is the new tacho your going to use ? how many rpm is that 10,000 rpm ?

LittleCharger
what is the cc of your heads now ?
and did you shave a lot off or fill the chambers with a bit of metal then machine them to get the smaller area.

when you measure the cc of the head do you fill it upto the chamfer on the head or include the chamfer with plug in ?
I am thinking to include the chamfer on the head with plug in tight ?

I need to find out what the cc of my heads are.


anyone know best way to take th bolts out of a motor that has never been apart since made in 1990 and used in salt (

[filthy phill]

on the cylinder head chamber sizing this is what I have always known.

this is from just one 2 stroke tuning page from Apilia, and they know a little bit about 2 stroke race motors !!!
same thing on every 2 stroke bine forum around. and go karts.

Cylinder-head shape also affects the powerband.
Generally speaking, a cylinder head with a small-diameter, deep combustion chamber and a wide squish band combined with a high compression ratio is
suited for low-end and midrange power.
A cylinder head with a wide, shallow chamber and a narrow squish band and a lower compression ratio is suited for high-rpm power.

so I am not understanding why this was done for a outboard 2 stroke that wants high rpm to go fast.

[hupiveneilija]

on the cylinder head chamber sizing this is what I have always known.

this is from just one 2 stroke tuning page from Apilia, and they know a little bit about 2 stroke race motors !!!
same thing on every 2 stroke bine forum around. and go karts.

Cylinder-head shape also affects the powerband.
Generally speaking, a cylinder head with a small-diameter, deep combustion chamber and a wide squish band combined with a high compression ratio is
suited for low-end and midrange power.
A cylinder head with a wide, shallow chamber and a narrow squish band and a lower compression ratio is suited for high-rpm power.

so I am not understanding why this was done for a outboard 2 stroke that wants high rpm to go fast.
Should I take it away of my engine because originally it was ment to be on bone stock fishing motor and make it more powerfull and crispier throttle response on midrange under 6000rpm? In a real life boating.
I know what it was made for before I got my hands on it. Saddly it works on my case too although its in a wrong use in my hands.

Phill You have to open your mind a little bit, not everything go by the book. There are people who are curious to try different things. Even here where hell freezes over.

That tachmeter for 8k I purchased yesterday dont work on my motor. Its propably for newer motors, cant adjust it 3cyl 2stroke. Have take it back to shop. :mad:

[filthy phill]

it is not a case of not trying things out, it is a case of a very well tried and proven thing over and over again, small combustion chambers do not give high speed power,
that is fact proven by major race teams and major engine tuners. and dont forget a race team dont even care what happens to the motor as long as it wins and last
till end of race.

smaller chambers Will give more low speed power/torque call it what you like. would be good for say water ski-ing or wake boarding as the speed is slow.

your small chamber head is not what has given you more rpm, that was the raised exhaust porting and the no limiter electrics..

shame about the tacho, what make is that one ?

[Per]

Phill, Don't know why the OMC engine looks the way it does but one thing is for sure, when Aprilia speaks about low to midrange they probably mean what we consider top RPM for our OMC 56" engines.

[hupiveneilija]

Another block. What a work from factory:mad:

[filthy phill]

yes that is typical craftsmanship from omc, I think they had stevie wonder working for them lining up the sleeves.

obviously no quality control was working that day.

what year was this ? 1992/3 ?

it is not even close to being right ha ha

[hupiveneilija]

Little update. Ign timing 17*>19*. Also made spring change for cooling. After slowing down from wot stopped engine, little thisnthat and measured head surface temp ~74*c.
Plugs look really good. As picture show in earlyer post.

Have to do something on prop/gearing to bring revs down a bit:p.

[filthy phill]

57 knots = 65.59
if your running the srx with extra cup lets say its 24 pitch,, slip will be around 10% so that means revs are around 7,750.

so all looking good.

as long as you can get it to last a good amount of time it sounds perfect.

I would think if you go bigger prop you will suffer too much on the take off.

what is your goal / what exactly would be perfect for you ? top speed ? or general use /

will this be for racing or for fun ?

[hupiveneilija]

For fun. Now I think its most usable for 1or 2person onboard. I can get more speed out of it for changing taller prop but use with two might suffer, dont know yet. If it has enough power then wont. On to do list.

Should try 1mm headgasket instead of 1.5mm.

[filthy phill]

if you have 1mm gasket it would give more compression, but I think I would be happy how it is.

what is the pull away like ? if already good then leave it like it is, if you need more pull away then maybe the 1mm gasket ?

just remember the more it revs, the faster it will wear out.

need to know what the rpm is.

[filthy phill]

pulling apart all these powerheads, have you had problems with removing cylinder head bolts ?
do you use a ratchet with socket or a impact gun to take them out.

where did you get the different sizes of head gaskets ?

[hupiveneilija]

No problems, use ratchet&socket. Only 2 broken earth studs on exhaust/water cover.

Sierra is 1,5mm and 1mm is in a ProMarine gasketkit.

[LittleCharger]

No problems, use ratchet&socket. Only 2 broken earth studs on exhaust/water cover.

Sierra is 1,5mm and 1mm is in a ProMarine gasketkit.

WSM and BRP are both 1mm as well.

Put the big pitch on her and spin her up!

[hupiveneilija]

Put the big pitch on her and spin her up!

First have to find one! Its not easy.
Asked about 2 blades on other topic.

Hey, its fishing motor. Not suppose to go almost 58kn😂😂.

Btw can one hear too early ign timing or is it just little driving and take plugs out to see them.
Sligthly tempted to try more timing.

[LittleCharger]

First have to find one! Its not easy.
Asked about 2 blades on other topic.

Hey, its fishing motor. Not suppose to go almost 58kn😂😂.

Btw can one hear too early ign timing or is it just little driving and take plugs out to see them.
Sligthly tempted to try more timing.

You can hear if you know what you are listening for but most of the time people find out to late lol...some guys run 21 but they typically drag race.

Two blade are not as efficient I'd look for a three blade.

Good speed should be able to get another couple mph out with some bigger pitch

[hupiveneilija]

You can hear if you know what you are listening for but most of the time people find out to late lol...some guys run 21 but they typically drag race.

Two blade are not as efficient I'd look for a three blade.

Good speed should be able to get another couple mph out with some bigger pitch

Have to concentrate on 3blade, might be also better when things get rough and choppy.

Think that smallchamber head have better control on combustion and firing, so it might be able to use more timing. Have to keep things on a rich side.

Hah, had cold ring under *** yesterday; tought that something is happening cause engine started to slowing down repeatedly. My bad had forgotten airscrew on the tank closed, so tank was all sucked in. Open screw and off you go!😂

[filthy phill]

there is lots of props for sale but all too far away in the usa and the price for postage is just so expensive, plus taxes.

can always get a srx for a v6 and get rehubbed for 13 spline. and take down to 14 inch diameter.

if you have a press you could do this yourself, just make a ring to help guide it in with dish washing soap for lubricant.

but again its hard to find the right sizes here in Europe.

[hupiveneilija]

Some stuffing.

Went testing today. These stuffings over the reeds, with white plastics on place its a little stronger under 4000rpm but on high rpms kind of fighting against itself and is not revving freely. Lost about 4kn on top speed. So leaving only that blue epoxy on its place. Might try also with Boyesen reeds, then its without stop plates and epoxy what makes primary comp even lower. Will see how it works.

[filthy phill]

Air temperature and pressure will slow you down today by a good amount.
today all across Europe the temp as gone up a few degree and barometric air pressure is at a real high today and tomorrow, that will make boat slower.

I think trying to use that blue stuff for stuffing the crankcase will fail time after time. its not going to be ethanol proof !!!!
its not the gasoline/petrol that will break it down its the oil and the ethanol that will cause its destruction.

you need to find out compression and revs before you do anything else, maybe your compression is above the 160 psi mark ?
you might need to find some high octane fuel and try that next, if compression is over 160 psi that just might be a problem.

the reeds you already have are what make ? they are not omc reeds.

[LittleCharger]

Went testing today. These stuffings over the reeds, with white plastics on place its a little stronger under 4000rpm but on high rpms kind of fighting against itself and is not revving freely. Lost about 4kn on top speed. So leaving only that blue epoxy on its place. Might try also with Boyesen reeds, then its without stop plates and epoxy what makes primary comp even lower. Will see how it works.

Hard to believe the stuffing is knocking that much mph off, typically increasing crankcase compression has little effect on top end.

I don't think you will find any more mph in reed changes either.

Air temp and pressure do impact as Phil commented but not 4 knots in our experience from the best fall days to worst summer humid days.

Compression is the best bang for the buck I'd focus on increasing it, I think you mentioned you are 145ish ?

[hupiveneilija]

Hard to believe the stuffing is knocking that much mph off, typically increasing crankcase compression has little effect on top end.

I don't think you will find any more mph in reed changes either.

Air temp and pressure do impact as Phil commented but not 4 knots in our experience from the best fall days to worst summer humid days.

Compression is the best bang for the buck I'd focus on increasing it, I think you mentioned you are 145ish ?

Came just from testdrive 2person and full tank 40l. 54kn with 2, 56kn with one. Took plastics away, spins more freely on top. 3kn more than yesterday. Those are driven wind behind the back. Other way 2kn lower. It was cooler week ago when I went 57,4kn, today much warmer, propably too rich.
But yes have to take that comp higher somehow, that 0,5mm thinner gasket might help a little allthough my engine has quite worn pistons&rings. Have to take that head to machine shop and take half mm off of it.

It sounds kind of a healthier now. Measured comp psi on warm engine between 145-150. Could use more.

I have another block wich Ive cleaned up, have to take 0,5mm off of a deck heigth and then put smallchamber on it with 1mm gasket.

[filthy phill]

forget the small chamber head, get a normal head and take off 1.5mm then you will have the compression bumped up very high.
you want top end power for the high speed, normal combustion chamber width is best for higher speed.

and the weather is not just the hotter air, it is very high pressure these last few days, that will slow you down maybe 2-3mph compared to the
cold low pressure weather a week ago.

what ratio are you using for the 2 stroke oil/petrol mix ? and what 2 stroke oil you using.

[LittleCharger]

forget the small chamber head, get a normal head and take off 1.5mm then you will have the compression bumped up very high.
you want top end power for the high speed, normal combustion chamber width is best for higher speed.

and the weather is not just the hotter air, it is very high pressure these last few days, that will slow you down maybe 2-3mph compared to the
cold low pressure weather a week ago.

what ratio are you using for the 2 stroke oil/petrol mix ? and what 2 stroke oil you using.

High pressure is actually your friend from a power point of view.

Need to consider elevation, humidity, pressure and air temp to determine relative air density which is what you want to jet off of.

[hupiveneilija]

Carb photo. And now someone who REALLY knows, should I go with the biggest version?

[hupiveneilija]

Wich one to use?

[hupiveneilija]

Some carbs.

[filthy phill]

the carbs you have 2nd from left are NOT 70hp carbs.
the black tops came on 60 and 70 from 1992 onwards, and all oval port triples.
they are definitely not 70hp as wrong size venturi and throat. the smallest of the 70hp black top carbs for a 70hp is throat 1.5 inch with 1.25 venturi.

no 70hp 56 cu in motors came with carbs with throats smaller than 1.5 inch and 1.25 venturi until 1999/200....
during 1999 anything was put on all sorts of models just to finish them off.

the 60hp black tops are the ones with smaller venturi, but not those you have there. what did they come on ? they are NOT from a 56 cu in..

here is the difference between 60hp and 70hp black tops for the 56 cu in motors.

the 70hp has 1.5 inch throat minimum..
.

[hupiveneilija]

the carbs you have 2nd from left are NOT 70hp carbs.
the black tops came on 60 and 70 from 1992 onwards, and all oval port triples.
they are definitely not 70hp as wrong size venturi and throat. the smallest of the 70hp black top carbs for a 70hp is throat 1.5 inch with 1.25 venturi.

no 70hp 56 cu in motors came with carbs with throats smaller than 1.5 inch and 1.25 venturi until 1999/200....
during 1999 anything was put on all sorts of models just to finish them off.

the 60hp black tops are the ones with smaller venturi, but not those you have there. what did they come on ? they are NOT from a 56 cu in..

here is the difference between 60hp and 70hp black tops for the 56 cu in motors.

the 70hp has 1.5 inch throat minimum..
.

Put carb on the right to intakemanifold to see if it is as big as round hole on intake is.

[filthy phill]

1.50 throat at the back of carb is the size to fit intake manifold.
the smaller throats are just 60hp carbs.

[filthy phill]

one more thing.
the number on the carbs stamped 339172 is NOT the carb model number, it is just a casting number that lots of different carbs have, it dont mean anything.
what you need to find is the real number for these and that was on a very small tag on the carb bowls,
if you do not have the tag it is impossible to find what carbs they are.
BUT they look like mine with same jet sizes, but I have different size venturi and throat ??????

why omc did not stamp correct numbers on carbs is a mystery ha ah .

[hupiveneilija]

Hey Phill, but that caliper on your biggest carb throat and take picture to see. To intake side.

[filthy phill]

I have pics already. will find them and posy them. Like you my motor was originally 60hp. So I got the bigger 70hp carbs. That is only difference on motors.
BUT if you ran small carbs then it is impossible to reach 6700rpm. Don't care who says it can or what gauge shows. It will only get to 6500 even with just test prop of 13 pitch. You will not reach 50 knots with small carbs unless you drop the boat from aeroplane.

[filthy phill]

on all the black top carbs the throat is same size at front of carb at air box 1.5 inches....
on 60hp black top carb throat at the back is 1.25 inches = 31.6mm.
on 70hp black top carbs throat at the back is 1.50 inches = 38mm.



your carbs with number 434159 are for 1991 65hp commercial ..


are you saying that you get 7,000 rpm plus using small carbs ?

[hupiveneilija]

are you saying that you get 7,000 rpm plus using small carbs ?

Yes, with 1.21/1.37. Aint that funny!

👌

[hupiveneilija]

Want to see that caliper on the throat!

[LittleCharger]

Yes, with 1.21/1.37. Aint that funny!

��

you must have a bad tach :o

[hupiveneilija]

Yes,im so glad it stops everytime 7100 so cant be afraid of revving it too much!😂😂

Do have meter to 8k but have to calibrate it somehow. There is tiny hole behind it, just need to know exact rpm so can adjust it.

[filthy phill]

do you think I only have the small 60hp carbs ? ha ha now that is funny

I have 3 sets of black top 56 cu in oval port carbs,
2 sets are the small 60hp originals that came on both my 1995 60hp motors,( model BE60TLEOC )
and 1 set I got after searching for a long time to get the 70hp black top carbs.

I will take some new pics of both the 60 hp small carbs and 70hp big carbs over the next couple of weeks.
I will not be taking the big ones off until ive had a few runs with the boat over the next couple of weeks.
I started it up today, first time since about September and even running on stale fuel it idles fine and I let it run for about 40 minutes. even in 32 degree heat.

https://www.youtube.com/watch?v=KiN8772sGXc

https://www.youtube.com/watch?v=zdqbicMmv0c

[hupiveneilija]

do you think I only have the small 60hp carbs ?





No I dont but would like to see how You measure them, so that i can measure mine right.

[hupiveneilija]

Request for the audience.
On the left Stock 329835-1 head milled -3mm. That leaves 2,6mm material thicknes in the thermostat opening. I think someone somewhere wrote that 0.1in is aprox the limit where these heads start warping more easily.
So this is what goes to the engine next. If its not enough then take more off of it.

Had long conversation with the guy who did small chamber head. He was suprised that it streches so up on rpms, especially cause it was made for stock rev range. Although he made it so that it dont cut revving like a knife but let the motor spin up.
For the next summer he will make a specific head for my use considering all other mods i make, durations and so on.

So we will see how it goes.

[filthy phill]

wow 3mm is a lot to have taken off, that is 118 thou !!!!!

you might just about be lucky with this much taken off .
I think normally people only take off a max of 80 thou, some racers have gone to extreme of 100 thou ?

you need to put the chamfer back as it acts as a transition area between the squish-band and the combustion chamber itself.
the angle of chamfer needs to be like the original.
with this much off the head you should have extremely high compression.

hope that works good for you and does not get distorted..

[Steves Jem]

Rather than referring to the amount that is taken off, all should be referenced to the standard SST60 head which has a combustion chamber depth of 0.450 in and allowable limits of +or- 0.010. When I use to race the modified 56ci had two heads that measured 0.400 and 0.380. These had compression over 200 psi but trying to remember 20 years ago is a bit difficult. I think it was around 220 psi. While the .400 head was fine the .380 started to crack and warp.

Stephen

[LittleCharger]

I think based on what you have removed pocket depth is probably around 0.500, stocks heads vary so you could be on either side of this hence the reason Stephen refers to the pocket depth end result. I would suspect that Stephen's motor was decked to at least the sst60 specs as well.

[filthy phill]

little charger is right, its the depth of the pocket or depth of combustion chamber how ever you want to say it.
if you had a low compression head to start with you could be fine ?


you just need to measure the depth of the chamber on this now ?

I will also check out what my spare head is today as well, mine is the later version head part number omc 339221.
will be interesting to see how deep that is at the moment.

[hupiveneilija]

I think based on what you have removed pocket depth is probably around 0.500, stocks heads vary so you could be on either side of this hence the reason Stephen refers to the pocket depth end result. I would suspect that Stephen's motor was decked to at least the sst60 specs as well.
LC you are almost spot on. Chamber depth is 0.513 now. But you have to leave something material to the thermostat opening. How much is it, somewhere on Hpbc site is mensioned 0,1in before it starts warping more easily. But hardcore racers migth change the head more often than pleasure boaters, thats why I left 0,1in there.
Combustionchamber is 5cc bigger than my small one so psi migth be somewhat lower.

[hupiveneilija]

Rather than referring to the amount that is taken off, all should be referenced to the standard SST60 head which has a combustion chamber depth of 0.450 in and allowable limits of +or- 0.010. When I use to race the modified 56ci had two heads that measured 0.400 and 0.380. These had compression over 200 psi but trying to remember 20 years ago is a bit difficult. I think it was around 220 psi. While the .400 head was fine the .380 started to crack and warp.

Stephen

With so minimal depth what happens to that thermostat hole?
I would like as much comp with my ex duration as I can.

Youre not using normal pump gas on those psi readings, right?

[hupiveneilija]

Okay, question. Now with those "smallbigcarbs" i have 56 jets in use but with 1,50in bigcarbs should i start some 60 jet size? Or go as big as sst60?

Does anyone know do all these carbs have same floatvalve seat diam? Because if main jet is bigger than floatvalve its supposed to empty bowl. Am i right?

[filthy phill]

Where the main jets are the seat is the same size.
these do not fit like a adjustable needle, they thread in and just have the hole straight through them.

with 1.5 inch throat at rear they are the carbs you should use... they have larger venturi.
if using the older style big carbs then jet similar to sst60 if you have taken the porting to sst60 specification.
you have basically turned the block into sst60 anyway. apart from not shaving the deck.

so jet similar to SST60 if you have compression over 160. over 160 compression needs higher octane fuel. higher than you
can buy in finland at car petrol stations.
your car fuel is low octane 95 e10 and 98e5 .... 95 e10 for example is only realy about 89 usa octane and finland 98e5 is about 93 usa octane.
you need real 100 octane or more if over 160 psi...
if you get a reading of say 200 psi then you will be needing special race fuel, and that is going to cost you a fortune in finland..

.
Can you explain a bit more about thermostat problem ?..... I am not understanding what you mean
.
.

[hupiveneilija]

.
Can you explain a bit more about thermostat problem ?..... I am not understanding what you mean
.
.

You should open once one of these engines and have the parts on Your hands to look at them properly. Then You understand.
Ive read things here and there with tought and understanding what Ive read.

Oh btw Im wrenching my o/b at the time. Means that Im doing things.

[LittleCharger]

With so minimal depth what happens to that thermostat hole?
I would like as much comp with my ex duration as I can.

Youre not using normal pump gas on those psi readings, right?

we don't run a thermostat but still enough meat in the head at the sst60 spec and even steve's depth's. I have one head that has 1.5mm at the thermostat hole

if you run the bigger carbs step the jetting up to 72 or 73 and do a quick test pass check your jetting and work your way down if need be, fat is your friend.

[hupiveneilija]

we don't run a thermostat but still enough meat in the head at the sst60 spec and even steve's depth's. I have one head that has 1.5mm at the thermostat hole

if you run the bigger carbs step the jetting up to 72 or 73 and do a quick test pass check your jetting and work your way down if need be, fat is your friend.

Well I have 2,6mm there and pocket depth is that 0,513=13mm. If I take it to the 0,440=11,2mm that leaves 0,8mm material thicknes there. Is that too little?
I measured psi under 130 on every hole with 1,2mm gasket. Now my small head with 1mm gasket 145to147. Was with 1,5mm gasket, quite squish!
Remember i have ex dur 180*.

Think could use little more fuel?

[Hevi Kevi]

I'm not sure what big bore carbs you're planning to use but I thought I should let you know the jetting could be different from one to the next. The SST-60 style carbs (which if I remember right are the same as the '86-'89 70hp carbs) and the older 75hp carbs are jetted about the same but the newer 70hp carbs have an extra adjustment screw on them up by the base and take a much smaller main jet. I don't know exact numbers but likely around 10 jet sizes.

Kevin

[hupiveneilija]

I'm not sure what big bore carbs you're planning to use but I thought I should let you know the jetting could be different from one to the next. The SST-60 style carbs (which if I remember right are the same as the '86-'89 70hp carbs) and the older 75hp carbs are jetted about the same but the newer 70hp carbs have an extra adjustment screw on them up by the base and take a much smaller main jet. I don't know exact numbers but likely around 10 jet sizes.

Kevin

Those are i think from older 2cyl 60hp. Have removed chokeflaps and modified needlescrew in place of idle jet. Original with 56 jets. Those up pipes inside the bowl has much to do every invidual carb model i guess. But what size to start?

[filthy phill]

just because your English dont come across good, do not think I am an idiot.....you should try to explain a bit more what your problem is.

you say the thermostat hole ? wtf is that supposed to mean ? why are you worried about thermostat when you only use a butchered one anyway ?
do you mean thermostat will not fit now ?
or do you mean the recess has been shaved away letting the thermostat fall though ?
or do you mean the thermostat itself has a hole in it ?

As said I would do earlier I Just measured Original 56 later style cylinder head part number 339221 the pocket depth is 0.5315 (13.5mm) and the volume of the chamber is 32.1cc.
CC was measured with the plug hole taped over and filled to be exactly level with top of the head surface inc the chamfer.
this is standard from factory never been touched since it was new.
also measured across the chamber and it is 54 mm at bottom of chamfer ( 2.12598 inches ) and 58mm at the top of chamfer ( 2.2834 inches ).
chamfer is 4mm deep (0.1574 inches).

used medical syringe to find the volume and used accurate and calibrated Steel Vernier Caliper and then checked with cheap digital vernier gauge.
amazingly the cheap digital was giving exactly the same dimensions..

" You should open once one of these engines and have the parts on Your hands to look at them properly. Then You understand."

As for me taking one of these engines apart and looking into the internals, I only got down this far on the top bit..

[hupiveneilija]

just because your English dont come across good, do not think I am an idiot.....you should try to explain a bit more what your problem is.

you say the thermostat hole ? wtf is that supposed to mean ? why are you worried about thermostat when you only use a butchered one anyway ?
do you mean thermostat will not fit now ?
or do you mean the recess has been shaved away letting the thermostat fall though ?
or do you mean the thermostat itself has a hole in it ?

As said I would do earlier I Just measured Original 56 later style cylinder head part number 339221 the pocket depth is 0.5315 (13.5mm) and the volume of the chamber is 32.1cc.
CC was measured with the plug hole taped over and filled to be exactly level with top of the head surface inc the chamfer.
this is standard from factory never been touched since it was new.
also measured across the chamber and it is 54 mm at bottom of chamfer ( 2.12598 inches ) and 58mm at the top of chamfer ( 2.2834 inches ).
chamfer is 4mm deep (0.1574 inches).

used medical syringe to find the volume and used accurate and calibrated Steel Vernier Caliper and then checked with cheap digital vernier gauge.
amazingly the cheap digital was giving exactly the same dimensions..

" You should open once one of these engines and have the parts on Your hands to look at them properly. Then You understand."

As for me taking one of these engines apart and looking into the internals, I only got down this far on the top bit..

Its about material thicknes, how much you can shave before head starts warping.
And hey, nice to see engine torn apart.

[filthy phill]

SSt60 head has pocket depth of just 11.178 mm from surface to plug hole.

I just measured the thickness at the bottom of the head, total thickness as can be seen in the pic is 36mm = ( 1.37795 inches ).
thickness of metal at the hole for thermostat is 6mm = (0.2352 inches)...
I have been told these particular heads can be shaved safely 80 thou and that would take pocket depth to 11.45mm = (0.4514 inches), some have gone that
little bit extra and shaved it by 100 thou to make it 11.1 mm (0,440 inches) same as sst60 head.
thickness at the hole in the head where thermostat sits would then be just 3.46mm =(0.13622 inches).

I dont know the thickness of the earlier cylinder heads, maybe they were thinner or thicker I dont know.
maybe someone who has done this can tell you the thickness of the head before they started shaving it.


my engine got taken apart a long time ago, about 1.5 years... been finding and making parts ever since to finish it .
waiting on engineer to set up his machines. plus illness has kept it all very slow work.
will eventually get done but not to sst60 specs, as I dont have a lightweight tunnel for the motor to go on at those specs.
my priority is not racing just wanting to go from 6,00 to 7,000 rpm on same prop. maybe.

pics below of where I measured the total thickness of the head.

[LittleCharger]

Well I have 2,6mm there and pocket depth is that 0,513=13mm. If I take it to the 0,440=11,2mm that leaves 0,8mm material thicknes there. Is that too little?
I measured psi under 130 on every hole with 1,2mm gasket. Now my small head with 1mm gasket 145to147. Was with 1,5mm gasket, quite squish!
Remember i have ex dur 180*.

.

Think could use little more fuel?

8 mm is too thin in my opinion. Heads vary so much from the factory, I have one head with a .375 pocket and the thermostat area is 1.25 mm.

Yes your compression will be down some with that kinda duration but may also be down due to wear, a leak down test would let you know where your at .

Is that wash on the cylinders all from run time with the current porting. If it is your good on the fuel, fat for racing but good for the lake, the middle cylinder tends to run the leanest on that particular block. Give each cylinder what it wants.

[Hevi Kevi]

Those are i think from older 2cyl 60hp. Have removed chokeflaps and modified needlescrew in place of idle jet. Original with 56 jets. Those up pipes inside the bowl has much to do every invidual carb model i guess. But what size to start?

If they are from an older 2 cylinder, I would try what LC said and try 72's, 73s. All depends on how much compression you are planning to run it with and how much power it's making. The more power it makes, the more jet you'll need. If you're running at 180 psi and your mods are working well, you may need more than that... like 76's or more.

[hupiveneilija]

SSt60 head has pocket depth of just 11.178 mm from surface to plug hole.

I just measured the thickness at the bottom of the head, total thickness as can be seen in the pic is 36mm = ( 1.37795 inches ).
thickness of metal at the hole for thermostat is 6mm = (0.2352 inches)...
I have been told these particular heads can be shaved safely 80 thou and that would take pocket depth to 11.45mm = (0.4514 inches), some have gone that
little bit extra and shaved it by 100 thou to make it 11.1 mm (0,440 inches) same as sst60 head.
thickness at the hole in the head where thermostat sits would then be just 3.46mm =(0.13622 inches).

I dont know the thickness of the earlier cylinder heads, maybe they were thinner or thicker I dont know.
maybe someone who has done this can tell you the thickness of the head before they started shaving it.




Good morning,
It seems that sst60 and newer oval port heads are same allready lower combustionchamber cast and can be shaved even further. Older ones are cast with deeper chamber and can not be shaved to 0,440in because there is no material for that.

[hupiveneilija]

8 mm is too thin in my opinion. Heads vary so much from the factory, I have one head with a .375 pocket and the thermostat area is 1.25 mm.

Yes your compression will be down some with that kinda duration but may also be down due to wear, a leak down test would let you know where your at .

Is that wash on the cylinders all from run time with the current porting. If it is your good on the fuel, fat for racing but good for the lake, the middle cylinder tends to run the leanest on that particular block. Give each cylinder what it wants.

Yes its all from start with that block. It is quite worn so i dont expect more psi from it.
Jets are 56, 57, 56. Middle could be even bigger because 0,020 over size.
Im not starting to lean because we drive long periods wot.

Porting is ex 1,382 or 180* and boost level with transfers.

[hupiveneilija]

If they are from an older 2 cylinder, I would try what LC said and try 72's, 73s. All depends on how much compression you are planning to run it with and how much power it's making. The more power it makes, the more jet you'll need. If you're running at 180 psi and your mods are working well, you may need more than that... like 76's or more.

Start with 72, put new plugs on it and make wot pull to see how they look. That 147psi is max what i get now because worn block and those older heads cant be shaved low enough to get higher. CR is ~ 7.0:1 now with current ex timing.

[hupiveneilija]

SSt60 head has pocket depth of just 11.178 mm from surface to plug hole.

.

Thats known. If You have ovalport head in hands, would You measure pocket depth from that piece? I dont have any ovalport head.

[Steves Jem]

With so minimal depth what happens to that thermostat hole?
I would like as much comp with my ex duration as I can.

Youre not using normal pump gas on those psi readings, right?

Ran Leaded and unleaded Av Gas 100 octane. This motor was the 56ci bridge port finger ported block with the Mod 50 straight front and 1 in dual throat carbies and the flex flywheel. Ran on a 14ft racing mono similar to the T850 and pulled 8,000 rpm with the 25in cleaver. Averaged 88mph in a kilo and was clocked at 92mph one way.

Stephen

[filthy phill]

ok on my 1995 oval port cyl head ( omc part no 339221) the pocket depth from standard is 13.5 mm..... SST60 spec is minimum 11.176mm.


depth of thermostat hole on oval port head is 6mm. and thickness at bottom hole on cyl head is also 6mm. (photo to show bottom hole.)

so for me to have sst60 spec i need to shave off 2.324mm... this would still leave me with 3.676mm of metal at thermostat.



Also I just noticed on the front of the head just above no2 plug and under the omc M is a letter L on the casting, it sticks up a touch so is there from new.


.

[hupiveneilija]

ok on my 1995 oval port cyl head ( omc part no 339221) the pocket depth from standard is 13.5 mm..... SST60 spec is minimum 11.176mm.


depth of thermostat hole on oval port head is 6mm. and thickness at bottom hole on cyl head is also 6mm. (photo to show bottom hole.)

so for me to have sst60 spec i need to shave off 2.324mm... this would still leave me with 3.676mm of metal at thermostat.



Also I just noticed on the front of the head just above no2 plug and under the omc M is a letter L on the casting, it sticks up a touch so is there from new.


.

Thank You. It needs to be ovalport head to make it sst60 specs.

[filthy phill]

I dont know about that, because people were making their engines to same spec as sst60 before oval port engine was made ?
oval port did not come until 1993 in most parts of the world.

the oval port head for the 60hp and 70hp is the same part number,
the 50hp 3 cyl oval port is not the same number and is lower compression, I dont know the thickness of the 50hp head or depth of pocket...


on the thin cylinder head why not fill the bottom of the pocket to get correct depth ? then plug hole can then be re-taped and tiny bit machined from outside to
give correct depth for the spark plug.
this would save shaving the head too much by just adding a small amount of alloy in the pocket ?
maybe this is a bad Idea ? but if it can be done then it could be a simple solution to use any of the cyl heads .
for example have 2mm material put in the pock then just tiny shave and its perfect ?

all depends how easy to get thicker head ?

its just an idea that maybe could work I dont know ?
.

[hupiveneilija]

Hello all!

Our midsummer, 30 minutes to midnight almost full daylight.

Go for a boat ride or not, too many beers!
Enjoy, I do😎

[filthy phill]

Looks like you have a very bright night there, here it was like that until 10.30 pm.

beers and boats are not too good an idea when getting dark, too hard to find the little green bottles ha ha .

best go in proper daylight for testing.

[hupiveneilija]

Have anyone made this mod?

[filthy phill]

what mod ?

[Hevi Kevi]

Have anyone made this mod?

Yup

[LittleCharger]

Yup

yup

[filthy phill]

so come on what is the mod ?

surely not trying the adjustable main jet ?

[hupiveneilija]

Water, water everywhere! And thereby seized #3.
Thats racing😂😂

[hupiveneilija]

Nice to have mid open also. This might block water flow a little.

And tuner, stock left i mean down😂, picture is wrong way and other one is already shortened little but have to take little more off of the end.

[hupiveneilija]

Okay, tuner finished! Does it look about right?
2nd pic is cutline comparison.
Now its time to zzzzzzz. Good night!

[filthy phill]

length is about right for a tunnel from what I have been told on the tuners.
But the end needs to have a flair or bell end shape etc, its to do with resonance flowing out whatever that is ha ha .

hope i am wrong on that.
i would of split the exhaust and put a v in each side to bring it more like the original sst60 if possible.

what is all that welding thats been done on the exhaust lying on its side.

by the way sorry to hear you killed the motor.

[hupiveneilija]

Alive, again! 😂😂
Cleaned block, 0,513 head, little less ex timing.
Tomorrow testing day for the motor and new l/u. See how it goes.

https://youtu.be/D5BrTmrL4o0

[filthy phill]

Did this block need new rings ?
and did you hone it again ?

If you were here you could skim my spare oval port head for me and then you could give that a try to see if that is
what you need for sure.
this needs about 0.80 thou to be taken off, maybe even 0.100 to get rid of marks caused by a broken ring.
this will then give me a lot more compression at around 160 to 170 psi as I want to keep the reliefs for very slow running too.
160 -170 psi would be good on my engine for wake boarding, it is good at low end now, but can never have too much torque for boarding and slow trick ski-ing... might even give me an extra few rpm up top end.

Just for extra reference .
I just weighed the oval port cylinder head. bare head without thermostat cover =2 kilo plus 2 grams
( 4 pounds 7 ounces ).

[hupiveneilija]

Went to the ramp while ago to adjust ign timing.
Now i know what propably broke those headgaskets and how it sounds when there is too much ign advance! Ive managed to "sössiä,sohlata" with timing real bad on blue one. Now i put set screw in same lenght as blue had and daughter put foot to the pedal, voila' that same sound and adv around 27*, cant handle that much😂.

Timing adj 19*max and now it sounds good and feels really good. With my testprop boat on trailer it takes 6500rpm and noticed that butterflies arent even fully open.👍
Oh and changed cam on the carbs, put alu instead newer plastic one. Those are different profiles.

So exited to see how it performs tomorrow!

Its different block, i have few.

Btw, with sierra 1.5mm gasket it worked but when put 1mm gasket on it was too much.
But anyway be careful when adjusting timing, ive done something wrong in that procedure and thereby have had these problems ive got.

[filthy phill]

so basically this is normal 1991 cylinder head on a 56 block with just the exhaust raised ? and other ports cleaned up. ?
should be real nice once its run-in.
19 degree timing is 2 degree different ?
why run at 19 instead of the correct 17 degree ?............what is the max advance timing on sst60 ?

I hope this one is good for you, you have done a lot of work and have tried very hard to get to your goal.

need video of this engine going nice .

[hupiveneilija]

And one more, retorque those head bolts 2to 3 times after warming the engine. When i put that sierra gasket in place and tightened bolts 1 round and right after that 2nd round,
they went quite alot again.

[hupiveneilija]

Hi,
How much water pressure block can take? Or is there somekind of a upper limit? How much head gasket can take abuse from high pressure?
Ive got 1.5to1.9 in fullspeed and motor is 40*c after wot run. so i need to tighten the relief pressure spring to get flow little less and temp up.

Needle goes between those numbers because it was REALLY ruf water today, wind is awful.

[hupiveneilija]

1st pic is what you get for too much ign timing. 2nd when it breaks headgasket and leans mix and over heat piston.
But nothing that cant be fixed. Little solid hone use and new used piston, off you go!

It can tolerate quite much timing adv. with 1.5mm gasket compared to 1mm. When i get this back together have to check timing and take it 2* lower 'cause it worked good with that. Part of it because i dont have high comp pressure.

And i use copperhasket spray, dont know is it good or bad.

[filthy phill]

when you say
Ive got 1.5 to1.9 in fullspeed and motor is 40*c after wot run.
do you mean 1.5 to 1.9 BAR water pressure ? if so thats perfect. (21 psi to 27 psi) that is ideal pressure.

you need a thermostat to keep engine running at the right temperature, or you will destroy the block by running too cold.

timing at 17 to 19 is good, no more or it will again ruin the pistons and rings.

what is compression on this engine now , cold cranking on starter with no added oil put in the bores ?

what is your maximum rpm so far with this motor ?

40 deg c is way too cold, and you will be losing power.
if on the newer ignition you wont even be out of quickstart mode at 40c. that is only 104 f !!!!!

[hupiveneilija]

Yes BAR is the unit. I have to limit waterflow some how to get temp up a little that said put stock spring on thermo/pressure relief and take spacerplate away.
I have thermostat in place but dont know how much water pressure is too much for the motor.

And yes 40*c is way low for temp.

[filthy phill]

these can run at 40 to 45 psi water pressure no problem.
you used to get 2 gauges from omc zero to 30 psi and zero to 60 psi. that would be zero to 2 bar and zero to 4 bar.
so you are fine with water pressure..
remember if there is a bit too much there is also escapes built in the system for that, in the front of the leg and in the adaptor.

[hupiveneilija]

Okay, first; Do not use copper spray with headgasket!
I think it caused that water problem yesterday and before. When i took gasket off surface felt kind of a slippery what makes little leak, now without spray no problem.

2nd. Went ramp today to warm the engine so i can retorque bolts. With 1mm gasket in place and 21* ign timing, yes i know now that it can manage with something like 25* with 1mm gasket and more with thicker, dont ask HOW i know��. Didnt hear any sounds that dont belong there when made full throttle pulls with testprop and also in went 1.5mm~59 jets, up from 56.
Sounds nice��.

For the cooling. In place is thermostat, stock reliefspring and no adapterplate between head and thermcover.
Water pressure at idle is 0.6bar and 5000rpm 2bar. Warms pretty quick on idle to ~70*c and when made those wot pulls its ~50*c. Temp measured on head surface.

Looking forward tomorrow , going out if the wind is low enough. We have had crazy winds last 6 days yesterday approx 15to23m/s.

[filthy phill]

Hope you have a good run with motor.

those Jets is that with the smaller carbs or the bigger carbs ? ( bigger being 1.5 inch throat at the back )

50deg on full throttle is not too bad , 70 at idle is a little bit warm but not too much.


I know what crazy weather is like, 2 weeks ago we had 32 deg C then 4 days later everyone wearing winter clothes !!!
temp went down to 14 deg C within 2 days, realy crazy and then high winds and rain.

we are now forecast some good warm weather but maybe thunderstorms , no good for boating.
I am hoping to get out myself either Friday or Saturday if weather permits.
I need to test a couple of propellers to see if my idea has worked to raise bow.

[hupiveneilija]

To LC and Hevi Kevi, there is a chance that those 72 jets with 1.5in carbs were too small for starters. Have to try bigger jet when everything else is working. Thumbs up!
When i went testing them the engine behaved like what i tought was over rich situation but must have been other ways. MY bad! So naturally i went towards leaner wich i hope now was wrong way. But like i said have to give them a new chance.
Dont know for sure if they are from 75hp or older 2cyl but definetly need big jets, like you said that have run 78 with no problem.

[hupiveneilija]

You can hear if you know what you are listening for but most of the time people find out to late lol..

This is SO TRUE!

Now i know what to listen!

[filthy phill]

what carbs and jets were on the original motor you were running before you made nose cone ?

[hupiveneilija]

what carbs and jets were on the original motor you were running before you made nose cone ?

These 1992 70hp wich are in place now. 50D.

[hupiveneilija]

From left#1#2#3. This is after 10nmile, fullthrottle almost hole trip and wot last 1nmile.
59jets and timing 22*. Temp from head surface after shutdown little under 40*c, thats too low have to get higher or what? But where to restrict the flow? And 2.5bar pressure wot or its where meter stops.
Otherwise goes really nice, boat is 👌to drive even it was real choppy today.

Went 54kn 7400rpm, awfull wind facing front.

A friend of mine was riding along today with his Argo cat 21& 200xs Ros.

Need more this! 😂😂

[filthy phill]

54 knots ? that is pretty dam fast . it = 62mph .
to get that with a head winds is extremely good, and 7400 rpm she must sounds very good too.
photo shows the boat running pretty level,

the 1992 carb , is that 1.5 inch throat or 1.25 inch throat ?

on plugs no 3 looks to be best to me no 2 a bit lean maybe
and what colour 2 stroke oil are you using ? .. clear...red...blue...green ?

temp will be low if no thermostat fitted, too much water flow cooling it down, I would sooner have thermostat that restrict the flow any other way.
because to get correct temp at high rpm the water pressure would be far too low at slow running and idle.
with a thermostat it will be right all the time.

glad it is running good for you ....

[hupiveneilija]

1.37in throat. Thermostat is in place, but those water mods done to the block increase flow quite much. Have to lessen it.

I might leave #1 untouched and lean #3 little bit but first have to try with fresh plugs and see how they look.

Blue full synt 25:1=3.85%

[filthy phill]

With the spark plugs I thought number 3 plug looks best, slightly rich, but best for high rpm...?

where on the head are you taking the reading from ?
do you have a gauge fitted in the head or use a heat temp infra red gun ?

There is threaded hole in the head for the temp sender, it is on the right side of thermostat cover ( pic below)
the sender can be bought from any auto parts store as it is the same as used on cars, then I just bought a cheap durite temp gauge and ran
a single wire from gauge to the dash and a positive from other clocks, works perfect every time. and can see it when going along real easy.
simple to fit and dont need to be real tight as it is a tapered thread on the sender and no water to come out of like on cars when fitted into water gallery/housings.
the threaded area gives the temp of the head to the sender.

this way you know what is going on all the time and at what rpms. with this and water pressure gauge everything on the cooling is monitored on the test runs.


.

[hupiveneilija]

Ihave pressure fitting there. 3mm hole on the bottom.
Pistons after taking boat to trailer, few minutes of idling. From up 1,2,3. That is lower tr port.

[filthy phill]

what do you mean 3mm hole ?
are you saying you drilled through this area ?

[hupiveneilija]

what do you mean 3mm hole ?
are you saying you drilled through this area ?

Yep. Also have to use 8mm drill to get hloe deep enough for tempsender. Its now in contact with water. 4.5mm through hole now.

[hupiveneilija]

DONE!
My cockpit.

[filthy phill]

This is why your seeing such low temp readings. you are not getting the temp reading at the right place !!!! you are measuring the water not the head !!!
I have no idea what the water temp is meant to be on these, definitely not the same as head temp though.
on a car when water temp shows 88C the head temp will be way over 100C.... so maybe if you read the actual head temp you might already be at the right place..

think of the tell tale water, that never gets to 62c and that has come straight from the head ?? so water temp and head temp are 2 completely different things.
water temp will only be the similar to the head in a closed circuit system like a car or motor cycle with radiator etc.

next time I run my motor in the tank I will get temp reading of the head and temp reading of the tell tale water, I think it will be atleast 10c difference maybe more.


The new complete dash is plain simple and easy to see everything straight away, I like that dash very practical for a fast boat..

I like that 8,000 rpm tachometer, what make is that one ? is it a marine tacho ?
and I see the pressure gauges too, they work pretty good, and I like how you mounted that.you have given me an idea with the pressure gauge mounting ha ha
.

[hupiveneilija]

Water over the sender is like conductive material, it is not in a strait flow, see how it works. And that telltale is NOT coming from head, it comes from top of the block, 1st cavity under excover plate.

Tachometer is quicksilver made by Tflex.
Yes im very satisfied for the layout, simple and very readable. On the left i have RAM mount for 7in tablet as a plotter. Doesnt show on the picture.

[filthy phill]

you will never read the temp of the head by having cool water flow over the sender, that is defeating the object of how the engine is cooled.

get a heat gun and point it at the head when your gauge reads 50c you will see that the head temp is nothing like the water going through it.

outboard temp is always measured as head temp, not water temp...

the water is cooling the head so therefore it must be colder than the head for this to do any cooling, this colder water is also
cooling your sensor instead of letting you see the REAL temp of the head..
you are getting water temp with your set up.

I dont know if there are any specs around about the actual water temp in the cylinder head, I have never seen anything about this for an outboard !!!.

maybe someone else out there knows this spec ?

[LittleCharger]

Ihave pressure fitting there. 3mm hole on the bottom.
Pistons after taking boat to trailer, few minutes of idling. From up 1,2,3. That is lower tr port.

Were the piston tops clean when you put this one back together? if so you are running on the rich side in all three, nothing wrong with living on the rich side if your doing long wide open runs, it just means you can keep doing them without rebuilding lol

[filthy phill]

100% agree with LittleCharger , it is better to be slightly rich than leaned out and burn up another block.

I just measured the amount of water in the head at any one time, it holds a max of 250ml (= US 8.45 fluid ounces) including the thermostat housing.
( but not the cover, just level with housing).

[hupiveneilija]

Were the piston tops clean when you put this one back together? if so you are running on the rich side in all three, nothing wrong with living on the rich side if your doing long wide open runs, it just means you can keep doing them without rebuilding lol

Yes they were clean not polished. Its a lot on the rich side? Could lean little or what? But coming long run on weekend tells much, i dont do nothing now. After that have to see how pistons look.
Felt really good to run 20minutes full throttle almost hole time😬.

Think that stock jet is 50 and now 59, big difference, alltough i use 25:1 oil ratio.

Blue block waiting for putting together. That will tell what tuner cutting did.

[filthy phill]

when you put the 59 jet in the bottom, what di you put in the top ?
did you get new 59 jet or did you drill out the old ones ?

I think shorter tuner will give more top end ? be good to know for sure.
is the blue block porting the same as the last one ?
why 25 to1 if running fully synthetic ? that is way too much oil.

[hupiveneilija]

1&3 is 59, 2 59+.
Blue has more ex duration. Oil /manual: continous powerboating use 25:1.

[filthy phill]

did you make the jets this size ? or buy them ?
what size in the top jets ?

[hupiveneilija]

Drilled. Top is 32, fuel jet.

Anyone else, is 25:1 too much oil?

[filthy phill]

so originally your carb has 32D top and 50D bottom...but now you have 59D in bottom and still 32D in the top... it is working goof for you with your speed.


I am thinking put 55D in bottom mains of mine and maybe 60D in the top..at moment it is 50D bottom and 55D top.

Now I just need to find exact drill size for the 59/60 D jet..........

.

[hupiveneilija]

59=1.5mm