Fast Fred's OMC Mod 50 secrets Thread #2

[Mark75H]

Carry on here!

Here is a link to the beginning of the original thread: http://www.boatracingfacts.com/forums/showthread.php?t=2052

[Roy Hodges]

[QUOTE=Mark75H;67793]Carry on here.............................................. .............................
.................................................. .................................................. ..................................
I find all this very interesting , as I have 4 - 49 cube motors, including a 65 short shaft, a 70 powerhead on a hustler short shaft, a 70 long shaft w/power trim and a 19 75 -75 horse Hustler short shaft , that had been raced in Sport E .

[850cc racer]

so fred i have seen these cast in liners you have spoken about, both my 814cc blocks have them,... so what 49 cuber can i get to run those mcdaniels pistons in?? :eek::cool:

p.s. this is the best thread and site ever! i spend all day on here at work! :eek::D

[Fast Fred]

it's not easy to find a press in liner Mod50 case, if ya did you most likely need sleeves,???? i have not found any:(,

any way, castin works,:eek::cool:
<a href="http://tinypic.com" target="_blank"><img src="http://i44.tinypic.com/207sxw5.jpg" border="0" alt="Image and video hosting by TinyPic"></a>

[850cc racer]

ahhh well i am in business then, no havent found any without castin liners..

so to make this work with the mod50 pistons what clearances will i need etc? as you mentioned the 25hr life span will come into play...:eek:
im tipping it more then the .008?

[Fast Fred]

the piston +.008 be good, when She gets to temp She'll be that .004 -.0045 Mr. NERSTROM was lookin for.;)

She's guna get hot on the exhaust bridges, best not to make them toothpick thin, be best to back them out of the bore.:eek:

i'll get a fresh shot of the press in Mod50 case:eek::cool:

[Detroit Whitey]

Can anybody still get pistons from Phill? The Last i heard was he was out.

[johnsonracer]

Hey Fred,

Why you say to lose the Stacks?

[850cc racer]

hey there fred.. so my new 56cuber im building has finger ports however they are .500 wide :eek: so im thinking i dont want to make the holes in the piston that big.. or do i :confused: im thinking it dont matter if they arent the same width.. :rolleyes:

will post a thread on drilling my fingerports in my wiseco's then we can all share info :eek::cool:

[Fast Fred]

the stacks will speed up the air more, the low pressure at the Ventori will get too high and the mix will get too fat, slows her down.

don't think Phill has any bullets left, thinkin Sea-Way gots one ring at 3.030:eek::cool:

[Fast Fred]

.500 is big, you can Dee port the holes in the piston, think i gots a shot of what that looks like. what size were holes in the old piston, did any crack?

[Fast Fred]

Dee Ported:eek::cool:
<a href="http://tinypic.com" target="_blank"><img src="http://i39.tinypic.com/3088lzc.jpg" border="0" alt="Image and video hosting by TinyPic"></a>

[David Mason]

Can anybody still get pistons from Phill? The Last i heard was he was out.

Weisco will make a run of them if you buy a certain quatity. Maybe you can rally your troops to order a batch ?

[Mark75H]

Weisco will make a run of them if you buy a certain quatity. Maybe you can rally your troops to order a batch ?

Wasn't Dave Scott trying to round up an order of special Merc pistons last year? I think Wiesco's minimum was 100 units at something like $125 each. I think that gets you in the ball park

[850cc racer]

the piston ports were simalar size to the ones in the block none of them cracked., im doing the rest tonight, but just wanting to know whats good or bad.. im thinking they dont have to be the same, i might have a look at how we'd go making the ports like a D.. we've done one piston already and it looks good, only thing is i dont want to take too much meat out of the piston near the gudgeon.. but i may have to as at the moment the hole is quiet small..:eek:
ill try and get some photos

[seaward]

Dee Ported:eek::cool:
<a href="http://tinypic.com" target="_blank"><img src="http://i39.tinypic.com/3088lzc.jpg" border="0" alt="Image and video hosting by TinyPic"></a>
Looks like a Dick O'Dea port job on a 2.4 to me. Where the heck is Stellwagen, Ledges.
I'm orange, Texas about 20 miles from the gulf of Mexisludge in SE TX.
Hal Broomes

[seaward]

Looks like a Dick O'Dea port job on a 2.4 to me. Where the heck is Stellwagen, Ledges.
I'm orange, Texas about 20 miles from the gulf of Mexisludge in SE TX.
Hal Broomes
I forgot to add that they use the long finger port and the bottom hole on the piston later on.
Hal

[Bill Gohr]

I have a set of 3 new, McDaniels pistons if ya need them, 3.030

[David Mason]

Wasn't Dave Scott trying to round up an order of special Merc pistons last year? I think Wiesco's minimum was 100 units at something like $125 each. I think that gets you in the ball park

I believe you are close to the estimate Sam.

If you are going to run a batch of Weisco pistons in Mod 50 version, and don't want to oder such a large quantity, why not simply turn them ? Weisco's did not have the dome as the original Mod 50 did. So making your own could be a very easy job. Pro category does this a lot. I imagine a local machine shop could turn and mill pistons to match the Mod 50 exactly for a price, and you would not need to buy 100 sets.

[Fast Fred]

not seein why i would turn a Stinger piston down, then thare is the wirst pin hole:eek:

at Wiseco for 3 grand, it takes most of the day to set up, then they will run 12 pistons, then you need to spend more money:eek::cool:

[Phil McDaniel]

Seems as there might be enough interest in my pistons to have some more made. If so, I will have to have orders for at least 1/2(50) before I order. My order will consist of .020s, .030s, and .040s over standard bore(3.000). The quantities of each will be established upon the interest in each size. I talked to Wiseco about a month age and with my quote, the pistons will still be $100.00 ea. w/ rings,wrist pins, and clips. Have some rods and plenty of brgs. to convert to Mod-50 size(large) Brgs. and rods run $100.00 for each set. Rod $80/brg.$20. Let me know if interested. E-mail or call home-843-650-0400 or cell 843-446-7767. Phil

********** Dave or anyone else in setting clearence on your bore, PLEASE check the taper on my pistons as well as the Mod-50. You will find a greater taper than the stock/fishing. I like .004 Phil

[Fast Fred]

i'll take a set of .040 overs, got your note, look for it in the mail, thinkin friday.:cool:

[Fast Fred]

hears that 49 case with press in liners:eek:
<a href="http://tinypic.com" target="_blank"><img src="http://i41.tinypic.com/2628ieh.jpg" border="0" alt="Image and video hosting by TinyPic"></a>

[850cc racer]

very nice there fred.

this is my latest creation.:eek::cool:
custom throttle linkages, they were changed again after photo taken, straight in front.. you have to have one of those :cool:

http://img21.imageshack.us/img21/2064/dsc00170d.jpg (http://imageshack.us)

http://img17.imageshack.us/img17/8205/dsc00172a.jpg (http://imageshack.us)


http://img21.imageshack.us/img21/2148/dsc00176k.jpg (http://imageshack.us)

[Fast Fred]

workin on a 56er too:eek::cool:
<a href="http://tinypic.com" target="_blank"><img src="http://i41.tinypic.com/6j1zrc.jpg" border="0" alt="Image and video hosting by TinyPic"></a>

[NERSTROM]

The pressed sleeve die cast blocks were made by putting a special aluminum blank in the die, in place of the stock iron sleeves. After casting, the aluminum blank was carefully machined out leaving the intake and exhaust port passages. You could not tell a pressed sleeve block from a Tradewinds block without looking inside. These motors made a lot more power than the stock Mod 50 but Jack Leek would'nt let us use them since we had customers racing Tradewinds motors. The first one was raced by Jeff Brown at St. Louis, this was when we raced 15 minute heats. Jeff won by a big margin and started the OMC domination of Mod 50.

[Fast Fred]

i needs sleeves:eek::eek::cool: gots to get me some:cool::cool::eek:

[Fast Fred]

:eek::cool:
<a href="http://tinypic.com" target="_blank"><img src="http://i41.tinypic.com/2epkksg.jpg" border="0" alt="Image and video hosting by TinyPic"></a>

hey Deanster you out thare:cool:

[drossi]

i'm tuned in fred

you de-lurked me:eek:
the 56er looks good....keep the pics coming!

[Fast Fred]

hey 850, what triggers you got under that fly wheel, what is that flywheel from.:cool:

[Popa Sam]

I see you are using the oval port 56. Have you tested one of these against the bridged port?

[850cc racer]

Fred: that fly wheels just a standard 70 and then one day it met the lathe :eek:

Hey there Popa Sam, i had a bridgeport on it, it blew up.. and this was a spare block i had as the bridgeport needs sleeves i decided to just go with the one

[Fast Fred]

got some sleeves for this, guna resurrect it.:eek::eek::cool:
<a href="http://tinypic.com" target="_blank"><img src="http://i40.tinypic.com/2mez7o5.jpg" border="0" alt="Image and video hosting by TinyPic"></a>

[johnsonracer]

Question for everyone...

Would a 56ci benefit from being rotated anti clockwise like the m31 with the exhaust on the other side... Spinning backwards should move the thrust to the other side yes?

If a left hand gear box could be fitted to it would it show an increase?

[Fast Fred]

it would make about 10 more hp. LA sleeve got them sleeves, not sure who you talked to:eek:, but i ordered 3 of them:eek::cool:

[Fast Fred]

Hey Deanster, gots two Stinger 75 foots, new bearins and seals, bob's nose cone Fast Fred style goin on, i only needs one, you needs one??:cool:

this foot is on the X class Champs hull,
<a href="http://tinypic.com" target="_blank"><img src="http://i42.tinypic.com/30lexx1.jpg" border="0" alt="Image and video hosting by TinyPic"></a>

<a href="http://tinypic.com" target="_blank"><img src="http://i44.tinypic.com/2cdh6dt.jpg" border="0" alt="Image and video hosting by TinyPic"></a>

[johnsonracer]

I just emailed them... Dammit!! haha

How much each fred?

[Fast Fred]

$225.00 each:eek::eek::cool::eek:

[drossi]

sign me up & put it on my tab

[Roy Hodges]

[QUOTE=Fast Fred;69290]Hey Deanster, gots two Stinger 75 foots, new bearins and seals, bob's nose cone Fast Fred style goin on, i only needs one, you needs one??:cool:

this foot is on the X class Champs hull,
<a href="http://tinypic.com" target="_blank"><img src="http://i42.tinypic.com/30lexx1.jpg" border="0" alt="Image and video hosting by TinyPic"></a>

<a href="http://tinypic.com" target="_blank"><img src="http://i44.tinypic.com/2cdh6dt.jpg" border="0" alt="Image and video hosting by TinyPic".................................................. ........
.................................................. .................................................. ..................................
.................................................. .................................................. ..................................
May I ask why you put some other clamp bracket ( NOT OMC ?) on the MODUH ? HUH ?
is it narrower that the 3 cylinder omc bracket ?

[Fast Fred]

did it for the three ram tilt and trim, YamaRude:eek:

[Roy Hodges]

[QUOTE=Fast Fred;69339]did it for the three ram tilt and trim, YamaRude:..........................
.................................................. .................................................. ..................................
.................................................. .................................................. ..................................
I've never had the pleasure of seeing one up close . IAre the tilt & trim in this motor NOW ,in this picture ? if so, it's really hidden well. and which hoss powuh yamahammer it was donated from ? huh ? some of !

[Fast Fred]

i was usein that one to see if it would work, this is what it looks like when it's done:eek::cool: ya need a Yamaha Pro50 bracket:cool:
<a href="http://tinypic.com" target="_blank"><img src="http://i43.tinypic.com/2dma8o2.jpg" border="0" alt="Image and video hosting by TinyPic"></a>

[Fast Fred]

hay ima75man you got the part number for them jets, i don't have any, but i'll see
how the Boss Lady can do for me.:cool:

[Powerabout]

The pressed sleeve die cast blocks were made by putting a special aluminum blank in the die, in place of the stock iron sleeves. After casting, the aluminum blank was carefully machined out leaving the intake and exhaust port passages. You could not tell a pressed sleeve block from a Tradewinds block without looking inside. These motors made a lot more power than the stock Mod 50 but Jack Leek would'nt let us use them since we had customers racing Tradewinds motors. The first one was raced by Jeff Brown at St. Louis, this was when we raced 15 minute heats. Jeff won by a big margin and started the OMC domination of Mod 50.

Why did they make more power?
thanks
Powerabout

[Fast Fred]

the pressed in cools better, got the single vert exhaust bridge ,so you can oil it,
bigger reed blocks.:eek::cool:

[Mark75H]

the pressed in cools better, got the single vert exhaust bridge ,so you can oil it,
bigger reed blocks.:eek::cool:

Neither explains why it would make more power. Hopefully Mr Nerstrom will get back to us with the answer.

[Fast Fred]

bigger reed blocks:eek::cool::eek:

[Powerabout]

Behind the sleeve porting?

[Fast Fred]

had pressin liners, witch move the heat better, that aloud for bigger reed block
:cool:

[Roy Hodges]

Like I said in the personal message I sent you, You ought to have your own LITTLE foundry to cast small aluminum parts .

[Fast Fred]

the straight in front 1/2 must do some thin for it, cuzz thay used it on the 31m:cool:

[BRIAN HENDRICK]

A recent Yamaha catalog lists the CR of each cylinder in their triples.
They vary, I suspect due to the nuances of common exhaust manifold pulse tuning. The 70" triple lists CRs of 5.76, 5.67, and 5.86 for cylinders 1 thru 3 respectively. The 158" V6 lists a CR of 6.7 for 1 thru 4,
and 6.4 for 5 & 6. But odd how the triple's CR is highest on the bottom, the V6's[a pair of triples] has the lowest on the bottom:confused:
I can only think the charge ramming effect is greatest on the cylinders with the lowest CRs, and this would corelate directly to piston temps.
I suppose they develop the design by running the CRs up until the pistons start sticking or holing, and then reducing the cc's on the hot one until it cools down. I was wondering if any of the FEH or OPC triple guys are setting variable CRs ?, or jetting diffrently top to bottom.

[Mark75H]

I suppose they develop the design by running the CRs up until the pistons start sticking or holing, and then reducing the cc's on the hot one until it cools down.

And then dropping the CR 3 more notches to compensate for the fact that they can not control what boat the motor will be used on

[Fast Fred]

can't say i've ever seen one (a yamaha tripple 70hp) test out like that, seems they test out like the V6. higher at the top.

Fast Fred 5 star certafryed:eek::cool:

[Fast Fred]

<a href="http://tinypic.com" target="_blank"><img src="http://i41.tinypic.com/28u2qsn.jpg" border="0" alt="Image and video hosting by TinyPic"></a>:eek::cool:

[Fast Fred]

E-tec certafryed:eek::cool:

trunk monkey:eek::cool:

[Powerabout]

I guess lowering could be for 2 reasons?

1) slows the pulse down from that cylinder so the next one (120ish degrees away) gets less return pulse and possibly later?

2) Could have less CR due to the fact that it gets a very high return pulse and really stuffs the cylinder?

2 guesses really?

[Fast Fred]

Fueler Mod50:eek::cool:
<a href="http://tinypic.com" target="_blank"><img src="http://i39.tinypic.com/301hbi0.jpg" border="0" alt="Image and video hosting by TinyPic"></a>

[Mark75H]

I guess lowering could be for 2 reasons?

1) slows the pulse down from that cylinder so the next one (120ish degrees away) gets less return pulse and possibly later?

2) Could have less CR due to the fact that it gets a very high return pulse and really stuffs the cylinder?

2 guesses really?

I had to think about it for a long while. I think it is most likely that the compression is varied from cylinder to cylinder due to uneven cooling in the head and block. Other manufacturers have sometimes varied the ignition timing to compensate for this.

[Fast Fred]

on the yamaha, i've recut the head deck to even it up, number 3 allways comes up a bit short, was thinkin cuzz of the injector pump space the hole did not charge as well like 1 and 2.:cool::eek:

[Powerabout]

Fred
If you burn a piston in the Yam which one goes first?

[Tim Kurcz]

OK you OMC triple buffs, I've got an extra Mod-50 flywheel available for sale. Anyone interested send a message.

Tim

[Powerabout]

Tim
Is that the same as a M31 flexplate?
How many different race flywheels was there for the 49 ci?
Thanks
Powerabout

[Fast Fred]

number one allways burnt down on me, i was allways pushin timin.

only one 3 cyl race flywheel, the mod50 flex wheel.:cool:

[Powerabout]

Where do you get the long rod with the larger size small end?

and
Anyone know what the merc rod used was?

and
Best option for new pistons

I am trying to find out what you can build with new parts and what you need to scrounge
thanks

[Fast Fred]

Sea-way gots mod50 rods.

Sea-way or McDaniel on pistons, two ring pistons last longer.

? not sure what rods, and or if it worked.:eek::cool:

[Powerabout]

Thanks Fred

In a previous post you posted a port map suited to tunnel or hydro's saying that it was a bit high for a V bottom.
Was that map for the short or long rod set up?

Regards
Powerabout

[Fast Fred]

OMC 49cuber intake ports are in a high state of tune, for the most part it's finger ports on the intake side.

the map is the same for ether rod. my tunnel is DEEP, not much help from the air
to get on plain, she pulls the hull right on plain, witch is like two Vee hulls.:cool:

you can get what ever you need, even a new 31m :cool:

[Powerabout]

Here's a few bits of data
Do we assume all 75's have raised and chamfered exhaust ports and bigger carbs?
Enjoy
Powerabout
Rev 2 added inner exh plate

[Powerabout]

added gears and driveshaft
SST 60 same gears and shaft as 75HP Nitro from 1986 and on

[Powerabout]

Does anyone know if the part numbers posted on BRP's web site are current or could there still be SS's in them?
How up to date are the numbers?
Thanks

[Detroit Whitey]

the shifter dog is differnt from the nitro to the sst60.The 60 has larger lugs on the fwd side.Dont know why they didnt use that in the fishin gearcases

[Powerabout]

I believe the dog was a running change as the original was being damaged on over run in the corners.
So it came out years after the 75/Nitro was finished

[quty06]

any spcfic measurements for exhaust tuner, esp for 3 cyl engine

[Sam La Banco]

The heavy duty clutch dog was released for the 1990 race season, Pt.No. 336446 it may still be obtainable from Seaway Marine.

The production tunner length for the SST-60 is 7.69 inches (195.32mm), from the bottom of the adaptor to the end of the meg.

[quty06]

tht mean just like expansion chamber always related to exh port, BTW thanks for info

[Powerabout]

Fred

Have you ever tried the late 70HP (92 to 98)flat top carbs on a 49ci?
What bore size are they?

They didnt use them on the SST 60...maybe there's my answer?
Cheers

Powerabout

[Danny Pigott]

Some may fine this interesting

[Powerabout]

great article but they missed the inner exhaust plate?

[Fast Fred]

<a href="http://tinypic.com" target="_blank"><img src="http://i44.tinypic.com/280iiwy.jpg" border="0" alt="Image and video hosting by TinyPic"></a>

[Fast Fred]

<a href="http://tinypic.com" target="_blank"><img src="http://i40.tinypic.com/2dtp15j.jpg" border="0" alt="Image and video hosting by TinyPic"></a>

[Fast Fred]

<a href="http://tinypic.com" target="_blank"><img src="http://i41.tinypic.com/f2qvqq.jpg" border="0" alt="Image and video hosting by TinyPic"></a>

got MO-HOG:eek:

[Fast Fred]

:eek:
<a href="http://tinypic.com" target="_blank"><img src="http://i42.tinypic.com/2dkzfjl.jpg" border="0" alt="Image and video hosting by TinyPic"></a>

[Fast Fred]

time for some nosecones:eek::cool: and fresh surface pearsing Drives:cool: cuzz you gots to have one:eek:
<a href="http://tinypic.com" target="_blank"><img src="http://i40.tinypic.com/nyeg05.jpg" border="0" alt="Image and video hosting by TinyPic"></a>

[Fast Fred]

:eek:
<a href="http://tinypic.com" target="_blank"><img src="http://i41.tinypic.com/2egfsj8.jpg" border="0" alt="Image and video hosting by TinyPic"></a>

[Powerabout]

Fred

Is that an SST 60 adapter or have you cast your own?

Powerabout

[Fast Fred]

it's a SEA-WAY addapter, i watned to buy all the three cyl molds, but i did not know Cees, or how to get a hold of him, i tryed, but never hooked up. SeaWay did buy all the molds, 3cyl, V6, and even V8, if i had got them i would not be happy if thay was makin Boot leg ones on me. so i will not make them on them.

[Powerabout]

Do you know if seaway still supply the sst 60 lower unit housing?

[sheuninck]

call and ask for doug

[seaward]

I would still like to know where the heck is Stellwagen Ledges.
Hal
Orange , Texas

[Fast Fred]

Stellwagon is east of Boston in the sad state of taxachewsus:eek:

last time i talked to dave he said they had a hole unit, said it sat on the shelf for a long time, no one wanted to pay the 2500 bucks for it, sold to some one in sweedin i think, but that was a wile back, maybe. i have one could maybe sell it. the best lu is a tricked out low water pickup Nitro.

[seaward]

Went there about 3 yrs. ago. For foliage . very expensive. Beautiful and we liked New H. except for state owned beverage stores. Lot's cheaper on the Gulf . Would like to know more about rubber tunnels.
Hal

[Fast Fred]

best to see as many different ones as you can, best place to go to see many is the Top O' Mi., power is not so easy to come by, but it is out thare. 3cyl 2 stroke 15" shaft is the only set up worth even goin after, a 4 stroke will work
but will never be the right set up, a 20" shaft will work according to some, but i would not waist my time or yours on it. thay are fun, not that 42' skater with 4 V10's in it i was think of or that Wing hull, but she is all that when she's lit;)

[sheuninck]

what size jets should I start with?

[Fast Fred]

what jets are in them carbs now? thinkin 73's are stock SST60:eek:

[Detroit Whitey]

start with stock sst60 jet set up if your running a 49ci if you gonna run a 56ci block you`ll have to go biger to break it in then do some plug reads and start from there but be carefull dont get those plugs to crispy

[Powerabout]

Fred the 3 cyl guru

What do you need to do to a 49ci 75hp to get it to perform the same as a SST60?
I need to put both into the same class (v bottom)and was wondering what mods to allow the 49 to catch up ( assuming th 56ci has a bit more due to the sst 60 porting, more cubes,longer rods etc)
Could I do it with just exhaust mods?

thanks

Powerabout

[river_ratj40]

on the 56 cu stock reed cages, how far can you increase the angle of the reed stops, using metal reeds.

i know it dont help alot, but heard it helps.

compare using metal reeds and increasing the angle to running fiber reeds. whats the best.(i know the benifits of fiber being easyier on your mota, hense one gets away and goes down the cylinder) but what about performance.

not going to turn more than 6 grand on tach.

[Fast Fred]

think it's best to give the 49er a 75# weight cut, so the 49 setup is lighter.
then if ya want to do any mods, you can do them across the board, keeps everybody happy,finger ports for all, ya! :eek::cool:

i'm not thinkin you'll see any gains, but, as far as you can, see what happens.

make sure it clears every thing, no hard bends so not to kink the reed.:cool:

[sheuninck]

1.] is there more than one type of carb, one with two screen vents and one with one screen vent? see attached pic. is there much difference in performance? I may need to buy another one with the two vents.
2.] with stock sst60 73D jets, the stinger ran slower then with the stinger carbs. stock 56ci 70hp has 65D jets, maybe i shoud try them?

[Fast Fred]

hows the burn look, musta been wet or black.

[Fast Fred]

the size of the outlet of the carb is important, the newer or different carb of the same outlet size may get a better power curve but thats all. once you get the mix (it's best to leanout a little at a time, big jumps could cost ya some pistons)
it will make more power and you will go fasta:eek::cool:

[sheuninck]

yea they were black and wet, the one with the odd carb was blacker. will try 69D. if too white will go back up, if still black will keep going down till brown

[Powerabout]

The SST 60 seams to have quite large mains...
I also dont quite see what model engine SST60 carbs came off or are they unique on the 60?

[Fast Fred]

Whitey !, you out thare, did you get any exhaust addapter specs? over all hight, just skim the bottom? what about the mounts?. lets me know if ya gots any thing, did find a spare 56er case.
thanks FF
water pick up toob hight too.:eek:

i'll look up them carbs, port hight thinkin be the key to it.:cool::eek::cool:

[Detroit Whitey]

Fred on the tuner i faced both sides shot the hole for the mounts and the power head.As for lenght you know your gonna have to play with that one i made mine so i could change between a couple of lenghts.Think i got a case. didnt get what you were talkin about on the water pick ups?

[Fast Fred]

theres got to be a spec sheet, the sst uncut is 2",the stock Stinger addapter is 1.750 tall, .250 thou' is a lot:eek::cool: i'll see if Dave has got them:cool:

[Popa Sam]

The SST 60 seams to have quite large mains...
I also dont quite see what model engine SST60 carbs came off or are they unique on the 60?

Beginning 1983 the Stinger had the same crankshaft and main bearings as the SST60. The mains were the same in prior years but the crank was cast rather than forged.

Later model Stingers and SST60 carbs are the same except jetting.

[sheuninck]

what was the difference in jetting?

[Popa Sam]

SST60 mains .073D. air .033.
Stinger mains .056D. air .025

[Powerabout]

Popa Sam
When I look in the web parts book on 75hp
1988 back to 83 have an idle mixture screw,
1982 back to 79 have 3 fuel jets
1978 back have 2 fuel jet carbs

70's did different things and some have an idle air jet like an sst

seems to have been lots of changes...
Powerabout

[Powerabout]

Guys

Whats different about the sst 60 cyl head over a stock 70?
I notice its a 2nd effort (Seaway) only part?

Thanks
Powerabout

[Popa Sam]

Guys

Whats different about the sst 60 cyl head over a stock 70?
I notice its a 2nd effort (Seaway) only part?

Thanks
Powerabout

About .060" to .120" depending on which model the 70 came from.

[Fast Fred]

it's countersunk, the squish band and the chamber are pushed up in. the stocker head is flat at the squish band, so on the SST head the crown of the piston goes by the head gasket and in to the head, on the stocker,the crown does not pass the deck of the case.:cool::eek::cool:

[Powerabout]

Fred


So the sst block has a lower deck height than a stocker?
Can yu make a sst block from from a stocker if you just get the sleves and deck it?
Is the squish band still flat with the piston surface or is it tapered from the outer edge?


Thanks

Powerabout

[Fast Fred]

you can cut the port map of the SST60 into the stock case. a solid mold case is stronger than lost foam. have yet to see a SST head, but i'm thinkin it has a flat or neutral squish band:cool: the deck hight is a set spec for the SST, not so much on the stocker, on the stocker the piston can not clear the deck thare is no room for it to do so. the crank spec on the throughs is +/- .011 thou which is a ton.

[Barry Strawn]

http://www.opcrace.com/TECH/60.doc

[Powerabout]

Ive got a 91 70 head off at the moment.
I'll measure it tomorrow.

[sheuninck]

SST60 mains .073D. air .033.
Stinger mains .056D. air .025
i cant seem to get the sst60 carbs to do better then the original flappers. tried 73, 69, 65 all brown (except the odd carb... all black), 69 was fastest, but still way slower. what are the air jets all about! do i need to match them when i change the main jets??? need a carb that matches the two i have with two vents... any out there?

[Powerabout]

On casting 329835-1
91 or early 92 70

Bowl is the same width at 2.120"

Depth from surface is way up at about 0.620" ( sst .440" min )
Thats a chunk of change
Thats enough to make the area at the thermostat too thin so maybe it is a different casting on the sst
The chamfer into the bowl looks very small on the sst rules drawing and my stock one would look the same if you milled it down that far.

Powerabout

[Fast Fred]

i can't open that doc. any exhaust addapter specs in thare?

the lo speed will influence the total mix, lo speed circuit never stops pullin through the power curve, some lo speed circuits will change from fuel to air with in the power curve.

i gots 3 or a set of 3jet carbs, thay are 1 1/2" carbs.:cool:

[Fast Fred]

(except the odd carb... all black), this is killin your set up, she needs all three to hit the same.:eek::cool:

[Fast Fred]

thanks David_L6, the tuna specs change for the SLT, but thats cool, guna take some measurements, i don't want to short change it out of any drive shaft:eek::cool:

[Roy Hodges]

[QUOTE=Fast Fred;74637]thanks David_L6, the tuna specs change for the SLT, but thats cool, guna take some measurements, i don't want to short change it out of any drive shaft:eek::cool................................... .................................................. ............................
.................................................. .................................................. ..................................
.................................................. .................................................. ..................................
EEK; - Cool ? It's frigid , man . I don't no wot to dew- My 1975 short shaft HUSTLER don't have a "TUNA" . I think it's got a mackerel or maybe a sea bass in it . SEW , wot i do, huh ?

[850cc racer]

ookay some help please people! this head good or bad to run with a set of mcdaniels pistons.. it had a set of dome tops in it before...

http://img190.imageshack.us/img190/6669/picture047yaa.jpg (http://img190.imageshack.us/i/picture047yaa.jpg/)

http://img200.imageshack.us/img200/1513/picture048hxh.jpg (http://img200.imageshack.us/i/picture048hxh.jpg/)

[Fast Fred]

it will work.:cool:

[850cc racer]

my dad reckons i should run a stock head as this will lower the compression too much due to the dish in it?

[Fast Fred]

your Dad is right, but if you deck it flat and use it, it will bring the comp up, and have a nice angle between the squish and the chamber.:cool:

[Fast Fred]

check your deck hight. if the head is not countersunk like that one, the pistons crowns need to stay even with the deck, the thickness of the crushed head gasket is the only clearance which is about .030 thou:cool:

[Fast Fred]

hay sheuninck,
i don't have one of them, i do have 3, 1 1/2" 3jet carbs, they are a set. i may or may not have the jets for them, eather way hows 75bucks sound, you pay your shippin. i'm makin it shippin week, be firin stuff outa hear, lets me know if ya needs them:cool::eek:

[sheuninck]

Fred,
What is the difference in these carbs, vs the sst60 carbs as far as performance goes?

[Fast Fred]

the 3jet carbs have an intermeadiat jet to help the moda move from lo speed to high speed. is it better than the SST carb, ? , thay should work just as good or better. late model Stingers had 3jet carbs on them from the factory, if you have an old style Stinger powerhead, (came with the smaller carbs) these would be an upgrade, you would go faster.:eek::cool:

[sheuninck]

fred. i sent you a pm

[Powerabout]

When you drop the Mod 50 pistons and the long rods in a 49er without altering the port timing how does it perform re the short rod motor?

[Phil McDaniel]

From the center of the rod(crank end) to the top of the piston port timing is the same on both short and long. As for ferformance:
shorter rods are faster on punch------- with a lot of piston/motor failure
longer rods are faster on top--------not much if any piston/motor failure

Reason; Shorter pistons have windows(ports) and are close to wrist pin.
Longer piston set-ups have no holes(unless added for finger and
boost ports)

HOW MANY HAVE YOU TORE UP????????? Phil

[Powerabout]

What I was getting at is the port timing is different not just the rod angle which helps the low/high torque with short/long rod issue as per any engine.

X amount more of crank rotation in the long rod engine will be required to uncover a port versus the short rod motor which sounds counter to the torque effect of the short/long rod motor story.
( you would need to lift the ports on the long rod motor to make the timing the same as the short rod motor)

http://www.torqsoft.net/piston-position.html

Has anyone ever measured the timing?

I have pulled many std pistons which have cracked so close to failure...they did always look ugly, i'm all for the long rod version with the raised pin.

[Fast Fred]

hey Phil McDaniel, made some room for ya in my PM box, that should go out today. think it's time for some more shots of Moda parts over hear.:eek::eek::cool:

[Bill Gohr]

From the center of the rod(crank end) to the top of the piston port timing is the same on both short and long. As for ferformance:
shorter rods are faster on punch------- with a lot of piston/motor failure
longer rods are faster on top--------not much if any piston/motor failure

Reason; Shorter pistons have windows(ports) and are close to wrist pin.
Longer piston set-ups have no holes(unless added for finger and
boost ports)

HOW MANY HAVE YOU TORE UP????????? Phil

Pistons will last longer also because of less piston rock near tdc.

[Tim Kurcz]

With respect to wrist pin location, please study engines other than the Mod-50. For a quick comparative study, go to the Wiseco catalog. You'll see something close to a 50/50 position quite common. SAE papers also confirm ring package stability (sealability) and piston/sleeve life are actually extended nearing a 50/50 position with respect to skirt length.

In the end, none of my FE engines ever mechanically failed a rod/piston, short or long. They all suffered thermo-dynamic failures, primarily due to a lean mixture condition (fuel starvation from one of several causes), and secondly due to excessive spark advance.

[Powerabout]

I rebuilt plenty of consumer engines that did big hours and either the noise from a cracked piston or the wrsit pin slogging out the pin bore gave the game up.
I do feel many of the boats were too heavy for the looper and we also had many twin rigs that should of had v4's.
The 2 cylinders ones on the other hand broke rods especially when over revved until both 2 and 3 had the upgraded rods and that fixed the problems.
I guess the piston was heavily built on the skirt to allow for the windows and the rod angle/side thrust which didnt help the weight with the small wrist pin....
That all history now...
So anyone checked their port timing after fitting long rods?

[Tim Kurcz]

Whoops boys.........

Guess I should have qualified my response: You're right, the factory cast pistons are known to crack, break, and blow chunks though the crankcase. This seldom does more than window the crankcase which quickly leads to engine stoppage.

What I'm talking about is race engines with forged Mod-50 or forged Wiseco pistons (service short rod style or McDaniels long rod style). None of these have ever broken. That said, typical lifespan for one of my race engines is 25hours (can be reduced to only minutes if run lean or over advanced).

Side note: We all know port timing is different between the short/long rod installations in the same bore. If nobody responds this week, I'll assemble and measure one (both ways) next week and publish the data.

[Powerabout]

Tim

I notice you run 2 pumps on your engines like a v6.
If a V4 can survive on one do you need 2 because the crank pulse is much lower on the 49/56?

and, OMC sold the SST 60 with an electric pump, which I would have thought unnecessary, was the above reason the issue?
I guess it all helps to prevent the China Syndrome

Thanks

[Tim Kurcz]

Indeed, I learned the expensive way that two pumps are needed when tall porting is used. Just a walk throught the pits tells me who is making power. If there's a single pump, most likely the motor is a pooch.

Taking a lesson from factory race teams, all my manual engines now use tandem pumps. My electric starts use an electric pump & regulator.

Beware to those who think jetting up is the solution. That will only drain your fuel bowls quicker, leading to a thermo-dynamic failure.

[Powerabout]

we also call it recycling...putting the aluminium on the sea bed from whence it came...a while back

[Roy Hodges]

I thought aluminum comes from Bauxite ore -the most common on earth, but expensive to
process (uses MUCH electrical power ) and magnesium is extracted from SALT water.

[Powerabout]

Correct it does and a place like OZ probably has a third of the worlds supply and OZ was under the sea for a few years while it was growing up.
Also explains all the other minerals and the salt problem we have in the middle.
Irrigate and we get salt.
http://en.wikipedia.org/wiki/Bauxite
Got the largest Diamond mine in the world as well...
and still high tax..so I moved

[David Mason]

I run one pump. I don't think mine is all that poochy.

[Powerabout]

What pressure do you get at WOT and what is WOT
thanks
Powerabout

[Tim Kurcz]

The OMC 49.9 triple is a known piston burner, so it's critical to confirm delivery pressure at rpm before hitting the race course. Having accumulated many offerings to the God of speed, I learned to feed the beast properly - the hard way.

All my manual triples now use tandem pumps and deliver >3.5 PSI @ 5000 RPM deadheaded through a 5/16" OMC primer bulb. My electrics are regulated to 3.5 PSI through a bypass return. These are the only two systems robust enough to keep these engines alive. The OMC service manual says these carbs are happy anywhere between 2.5 and 5 PSI. Fall below that for any reason and say hello to a new piston.

All that said, David Mason is indeed quite successful with one pump - probably on the ragged edge of delivery - and very lucky. But then again, port timing has everything to do with diaphram pump delivery. Perhaps he's running shorter porting than me.

Example: After burning down a piston, one of my customers tested his pump in a stock powerhead and again on his mod powerhead spun at 500 RPM on a test rig. The stocker delivered 17 oz/min, the same pump on the mod delivered only 11.5 oz/min. Adding a second pump to the mod, delivery increased to 18.5 oz/min. (All at zero pressure). This simple test proves the effect of port timing as it relates to diaphram pulse and pump performance.

Perhaps you've heard the saying: Too lean, too long, too bad! Tandem pumps or the electric system have eliminated piston burning due to fuel starvation. Now my efforts are concentrated on making more power.

[michael]

How do you connect up the second pump? Is it in series with the first?
Where do you get your pulse from, existing spot teed off to both pumps or a seperate spot?
Thanks

[David Mason]

Maybe if I try two pumps I can pick up some more speed. Worth a shot anyways.

Given there are a gazillion blocks out there to mess around with, I have tried a lot of different porting measures. Some worked, some not. I have not burned a lot of pistons, but I have burned a couple. Most of my burnt pistons result from failure in water pumps or to large a brass fitting that broke off. Smaller fitting with adequate diamenter is the way to go. The big blocky fittings will break sooner.

Most of the serious racers know basic porting and tall or short and how it reacts on race courses of different sizes.

I guess some new homework was just assigned to me this fall.

[Powerabout]

Does anyone know when they were making the first v6 how much work was done on working out which cylinders worked best for the 2 pumps?

[Powerabout]

Fred

Can you help me with a RIB issue?
What do you do to fix the problem of a rib that I think someone has cleaned with a solvent that has made the plastersizer in the hypalon go sticky?

Thanks
Powerabout

[Tim Kurcz]

Most of my engines run the pumps in series. OMC actually produces a suction and pusher pump combination that is used on V-4's V-6's and the 30and 35 HP triples. Recently, I've run two conventional pusher pumps in parallel to a closed loop. Either way, make sure you're delivering a minimum 3.5 PSI at 5000+. It's best to put a guage at the cockpit and observe what's happening down the straight.

Warning: With a single pump, installing bigger jets only serve to empty the carb bowls more quickly, burning a piston as you back off for the turn!

The second pump is run from a hole drilled and tapped in the #2 intake runner about the same position as the #3. This is best done with the CCase off the engine. You will blow chips into the engine. As the casting wall is thin, Use high strength Loctite to seal/lock the fitting in place.

[Powerabout]

was number 2 just convient or was it calcuated for the series pump set up?

[Tim Kurcz]

#2 was chosen for two reasons. 1) Shortest possible equal length pulse tubing can be used. Remember the tube increases CC volume. Keep them short as possible. 2) Use of a #1 pulse tube makes it almost impossible to install an electric starter. I prefer E-start.

[michael]

Has anyone ever compared output of a VRO pump vs the older style diapham pump? Which has better pressure and volume, or are they about the same?

[Powerabout]

The Vro pump will pump way more fuel but as one of the posters here has tested them on his V4 and found they can't cope once the engine gets to about 7k I think he said.
Understandable when you look at the size of the components

[Powerabout]

Hi Fred

Do you know if the 92 70 new style flywheel is lighter and or can be modded?
Is it diecast so we must leave it alone? They look sand cast ish?
SST 60's didnt use I wonder why?

Thanks

[Detroit Whitey]

find your self a 65hp pancake flywheel

[Tim Kurcz]

For cast aluminum flywheels, most of the strength is in the skin. Cutting these down is outright dangerous unless you add a scattershield to catch the schrapnel. Ductile iron flywheels are tougher and can be cut to some degree. Any cut down flywheel should be balanced and spin tested to 1.5 times the intended operating RPM. If you need electic start, the Mod50 flexplate flywheel is the best option for you.

Good luck!

[sheuninck]

72 was the only year for the Pankake flywheel. 9 lbs vs 10lbs on the others

[Popa Sam]

Hi Fred

Do you know if the 92 70 new style flywheel is lighter and or can be modded?
Is it diecast so we must leave it alone? They look sand cast ish?
SST 60's didnt use I wonder why?

Thanks

This flywheel came out after the SST60 and it's heavier.

[Phil McDaniel]

The pancake flywheel will work on the 49 and 56 motors with the newer style ignition. It will have to be cut on the hub like the SST 60/ fishing 56er to allow the black trigger to clear.

[Powerabout]

Ok
What do I need to know to make a flex plate for an OMC?
Could I machine the hub out and bolt that to the flex plate and then machine out outer ring to hold the charge coil magnets and bolt this to the flexplate....or install Merc components and use one of their flywheels??

Std flywheels are too ugly

for $350 i would buy one but its been a while since they were that price
Buy one and copy it to recoup the investment?
Is there any magic in the manufacturing of an OMC one?
Make a mold and make one from pre preg carbon?

[Detroit Whitey]

What are you trying do or achive by adding a light flywheel.Bet if ya put one on and did a blind test ya coulnd`nt even tell the differince.depends on the rig?

[Powerabout]

bet i could..

harder to start and bad idle

No your right not much gain except maybe on a drag boat.
But it will soften the load on the crank and top bearing when the engine moves around
If you have ever watched an inline merc running with the top cowl off you will be amazed at how far the gyroscope effect moves the ring gear even in calm water.
Of course we all know Evi's are tougher than Merc's

[Fast Fred]

:cool:

[sheuninck]

http://cgi.ebay.com/ebaymotors/65-HP-JOHNSON-OUTBOARD-WITH-CONTROLS-AND-WIRING_W0QQitemZ110438219174QQcmdZViewItemQQptZBoa t_Parts_Accessories_Gear?hash=item19b6a17da6&_trksid=p4506.c0.m245

[Fast Fred]

Hey Tim Kurcz, thanks man, that bypass regulator made it work, in the test tank. goin back on the hull tomorrow. see if i can get that ride around Minot light been lookin for:cool:. i'll snap some shots of the reg set up:eek::cool:

you the Man,
thanks
FF

[scud]

Arn't the rods that work with McDaniels pistons 1968 and newer 40hp twin rods p# 378375 ?

[850cc racer]

308301 :cool:

mod 50? yeh i gots one:eek:

[850cc racer]

Fred your threads a little bit quiet. you were going to bring your mod 50 back to life?? has that happened? :eek:

i cant wait to bring mine to life for the first time ever!!:cool:

[Fast Fred]

hey 850cc,
fuel regulator was a problem, she needed a return line so the fuel pressure does not back up and spike, fuel volume also was a problem after 5000.
i work on boats all day every day, not speed boats, i call them couch boats. i had to take it back off the boat and put her in the tank, i could not work out her problems and drive the hull at the same time. she slammed off the deck once really good. she make the best pull at 20deg :cool:

[Fast Fred]

i only got to make two pulls on this new regulator set up, the wind was blowin inland at about 20mph, so i had to hold her up so not to blow over,:eek: got a ways out to Minot light, feelin good that i could make it the rest of the way with no trouble, i made my turn, 180, lined up with the channel and rolled it ON, helled her up at about 7800, punched it two or three time to see if she was guna wash out, the power was still there, i knew the harbor Master be comin to get me after that pull, (ya they was hearin it down town) So only had time for One More Pull, at about the same distance, pushed it harder, she was pullin 8000 last i looked, i let her run up for a bit more, (the inlet openin in the breaker wall was comin up fast than ever before, ever:cool:) it's gettin cold now, most everbodys out of the water, the harbor Master was comin around the ben with the blue light on, i chugged over, she reminded me of the many times she has reminded me NOT to burn through there. dam if i don't just love to poach that piece O' water:eek::cool:;) Impressive is was what i was feelin.:cool:

[850cc racer]

Hey there Fred, well it sounds like she's going well. was the fuel pressure spkiking sky high wiht no return? what was the acceleration like? i bet you cant wait for the weather to warm up!!
i should have my Mod 50 in the next 24hrs. i have a few days off so ill be building MOD 50!! should be ready to light her up on the weekend.:cool:

850

[Tim Kurcz]

Glad to hear you're spooling now, Fred. Wish I'd figured out the return fuel system years ago - would have saved boxes-o-pistons! Mostly I'll run the engine to 8000+/-200 - seems to like it there. On a short course I'll prop down and have seen 8800, but it's over the peak at 8500. I don't recommend holding there long; remember where those rods came from!

Good luck in the spring.

Tim

[Fast Fred]

acceleration was right on, responded to all throttle inputs. was peddlin it a bunch on the way out. didn't mind off shore style on and off the peddle.

on the dyno hp peaks at 7400, she holds on to the peak to 7900, at 8000 she's just startin down the backside of the curve:cool:

[850cc racer]

sounds good fred!! im sure it'll make my hull super quick.

well i started playing with mine last night, just getting all the bullets and rods the same.. :cool::eek:

[formeone]

haa fred what advantage is the straight intake over the curved/ie stock angled intakehp or???... especially on the smaller v-rude tripple....

[Powerabout]

Looking at the previous photos there's 2 version of the twin barrel front half
a straight and a slightly angled one with the shift shaft cross shaft?
I also wonder how a custom straight in using the original 1 1/2 single barrel carbs and suitable reeds would work?

[Fast Fred]

the reed block is the limiting Factor, the bigger or more reeds you have, the more volume you can flow, more volume = more thermo energy = more power.

air don't like to turn, it will over run the turn and slow down.

now that i'm at this point, i'll build the Straight In Power head and put it on the Stinger mid. the factory never offered said unit, only the 19s power head had a
FT model.

only scorched one set of piston to get this far. need a set of +.060 :eek:

[Powerabout]

the reed block is the limiting Factor, the bigger or more reeds you have, the more volume you can flow, more volume = more thermo energy = more power.

air don't like to turn, it will over run the turn and slow down.

now that i'm at this point, i'll build the Straight In Power head and put it on the Stinger mid. the factory never offered said unit, only the 19s power head had a
FT model.

only scorched one set of piston to get this far. need a set of +.060 :eek:
Is there no issue with air speed when you make it large and it slows down or does it?

[Fast Fred]

would have to say no issue with air speed, lookin from hear.

75man, 38's low speed, 40 mains, she ran fat, made black soot on the cav plate , :cool:

[Powerabout]

Fred
How do you think a straight in with the original 1 1\2 75hp carbs would work?

[Fast Fred]

think low end would be killer, maybe, but thats all i would think.:cool:

thanks 75man,:cool:

[Powerabout]

I would have thought you would get a better top end due to less restiction?

[Tim Kurcz]

For Powerabout et. al.

Is this what you were thinking of?

Tim

[Powerabout]

exactly....
Are they std 75 carbs?
How did that configuration perform?

Many thanks for the photo
I think BRF needs to start a 'hall of fame' for your creations

[88workcar]

Put a picture of the otherside also Tim. Man that thing is purdy. You pay the shipping I'll give you $50.00 for it. :D

[Tim Kurcz]

I appreciate the thought!

This is my latest FE/850 engine that uses three conventional 1-1/2" throat OMC 1bbl carbs. Rich Welch saw 100.2 (GPS) on the Hillsdale front stretch in his new MJR hydro testing in early September. He played with the competition all weekend. We expect FE/850 records will fall next year.

Tim

[Powerabout]

Tim
Is that front half 2 pieces or should I say very short with a long reed plate?

[Tim Kurcz]

Remember the APBA rule states your FE/850 engine "must be a recognizable service block and crankcase". It's actually four sections including a narrow slice of the original crankcase.

[Powerabout]

huge area around the reeds.
You could fit a set of V Force reeds in there or 2 std sets? ( a 30 and a 45 degree set?)
Whats the scoop?

[Fast Fred]

how did you seal the original slice to the next section, i see how you bolted it up, but how did you seal them. do you help the exhaust port to sweep up for that style exhaust?

cool stuff.:cool:

[formeone]

cool tim,, just reading your thread,,, sounds like we both working on records,,,, you just have to enter the kilo traps at 105 mph to brake my record cool,, when i broke the record years/ages ago,,, i saw 106.5 2 runs i had,,,

[Tim Kurcz]

Thanks for the kudos, Fred & Co. Pretty tricky machine and fitting work - but gel-seal does the trick. Top exit exhaust eliminates uncontrolled water vapor intrusion which changes tuning - basically an improved (external) version of the Mod-50 system. Sounds great, too!

[Tim Kurcz]

You've got it Cheney, but closed course first. I'm certain it's capable of something like 110, but don't care to drive and open boat that fast for a kilo. Did you run a capsule?

[formeone]

nooo ran a modified apel 350 boat it was my everyday raceboat that i ran threw,,,, about 2" kicked under or more,,,, wouldnt do it again,,,,, in that small boat,,, i ran same set up at bakersfield always read just over 103 mph there till iggnition let go,,,, that about a mile almost i guess

[formeone]

sure luv the looks of that front case,,,, any production thoughts?????

[Tim Kurcz]

Yep, an FE on a 350 would be a white knuckle ride! I can appreciate you not wanting to do that again. 2" tuck - was that a D-Merc case? I run the 45SS case 1/8" under and hit 100 with ease, but have no desire to go any faster.

This is not a project for the begininer - complicated machine, welding, and fitting work. Because of that it's somewhat expensive. So, I don't plan production, but will consider making one or two more if there's demand.

[Powerabout]

Tim
How about the bell mouths on the carbs are they CNC'd or by hand?
Do you make them for sale?

PS What reed blocks were in there?

[Tim Kurcz]

Powerabout & all,

Indeed, I do make the "bell mouths" seen on my engines - CNC. They smooth out transitions and improve flow, and fit any OMC 1-1/2" throat 1bbl. $55 each includes screws. There are 18 available in stock.

The reed cages are my secret.

[Powerabout]

Tim
How about if the carb has an air jet at the front top ( rather than a fuel jet) like many of them, has that been allowed for?
Is that the notch I can see on the outer?

Regards

[Tim Kurcz]

Hi Powerabout,

The relief you see is the 10 O'clock vent. I will cut 12 O'clock reliefs for no additional $$$.

Tim

[Fast Fred]

hey Tim Kurcz, my exhaust pushed out at the base gasket, any tricks there to get them sealed up nice?
thanks
FF:cool:

[Tim Kurcz]

You betcha, Fred.

That joint is always a problem because the exhaust housing is machined separately from the block and tolerances don't always stack correctly.

The solution is to coat both sides of the gasket with Loctite Gel-Seal (OMC), otherwise known as 518 (industrial) or Master Gasket (consumer). This is an anaerobic sealant that cures through .015". Just be sure to let the joint cure for 24 hours before running the engine.

This method will seal any engine gasket forever (upside). Be aware the gasket forms a laminate structure, will be destroyed upon disassembly and is more difficult to remove than a failed plain gasket (minor downside).

BTW; I worked for Loctite for 26 years and was their engine/powertrain guru for race teams throughout the world. Our (unauthorized) catch phrase was; "Use Loctite or kiss your nuts goodbye".........

Tim

[Fast Fred]

:cool: i gots to go and fix some boats:), thanks:cool:

[formeone]

question,,, has anyone else had problems with the crank wabbling/bending,,,,, at the top,,, me bin haveing and have had problems that way alot,,, maybe better balance or????....

[Powerabout]

what problem did it cause?
pounded the top bearing in the case?

[formeone]

deff worked the bearing in the case,,,, and top bearin/crank blackish in coler have had this problem withboth motors now,,,,, different style cranks and flywheels,,, one was just rope pulley,,, other stock fishing flywheel...

[Fast Fred]

:eek::cool:<a href="http://tinypic.com" target="_blank"><img src="http://i50.tinypic.com/2qwzlup.jpg" border="0" alt="Image and video hosting by TinyPic"></a>

[Fast Fred]

camera $uck$,?:eek::mad:
<a href="http://tinypic.com" target="_blank"><img src="http://i49.tinypic.com/34yptsi.jpg" border="0" alt="Image and video hosting by TinyPic"></a>

[Fast Fred]

<a href="http://tinypic.com" target="_blank"><img src="http://i49.tinypic.com/qoj8tv.jpg" border="0" alt="Image and video hosting by TinyPic"></a>:eek::cool:

[genea01]

looks good what kind of boat you going to running that motor on

[Fast Fred]

<a href="http://tinypic.com" target="_blank"><img src="http://i49.tinypic.com/dbmf06.jpg" border="0" alt="Image and video hosting by TinyPic"></a>:eek::cool:

[ima75man]

fred, your pm box is packed..

[Fast Fred]

the first shot is an SST60, it's mostly NEW stuff, it's Modified, get ya DQed in SST60 class:cool: got the tiller on there:eek: lookin like an SLT moda.

then you got a fuel pressure regulator with a return line;)

[Powerabout]

Fred
a while back you were modding a SST 60 and you mentioned you were going to mill the exhaust off and modify it.
Did that ever go ahead?

Cheers

[Fast Fred]

i talked to a Dude that worked at OMC, he built Mod 50's for them. he said that thay took a 56 case put 2bbls on it with big reed blocks, and did the exhaust like i was thinkin, it only would make 102hp. i've heard tails of 110-115hp but can't say for sure. the said the carbs did not help it, or the exhaust. said the 56er did best with 1bbls and stock exhaust.

i'll let yas know how the 56er does side by side with a 19s:cool:

[Tim Kurcz]

Hi Fred,

Take a look at the attached schematic and you might consider doing a little more plumbing work. The engine looks like fun tiller style!

Tim

[Fast Fred]

the Mallory regulator wanted it set up like i have it, it has a Big needle in it,
the Loop is from the pump to the reg' then back to the tank. the pump never backs up, it's always free flowin, the needle adjustment forces fuel and psi to the fuel rail so there is about 80gals an hr available to the carbs if they want it,
but the pressure never changes.

any chance you could make the schematic bigger? i have a gauge at the top of the fuel rail to recheck the psi.:cool:

[Powerabout]

Fred
with that set up the regulator is contolling flow as well pressure.
If the reg is on the return side of your fuel rail it only controls the pressure.
Ya just need to be sure the reg can flow all the fuel at the regulated pressure, that you need.

If your fuel rail is a dead end then the only escape of any air in the fuel is through he carbs.
( I knows thats how OMC say to do it because they cannot tell you to have a return line as its against USCG regs)

Changing it around may not fix anything BUT it sure will eliminate a couple of potential problems.

Cheers
Powerabout

[Tim Kurcz]

Indeed, the benefits of the loop bypass system are elimination of air bubbles, constant flow/pressure through the fuel rail, and tremendous thermodynamic benefits should you employ the cool can. Yep, it's a bit complicated, but my experience is it absolutely eliminates burnt/detonated pistons due to fuel starvation. Thus the only fueling error becomes improper jetting. You know the saying: Too lean, too long, too bad! Will make a better schematic and post sometime later.

Tim

[Mark75H]

Thanks for the diagram, Tim.

I have been considering a cool can for 850, but could not figure out how to really get enough BTU's removed from the bowls and lines without a lot of bulky insulation.

This set up would also allow pre-cooling the whole tank of fuel ... you have probably made me a very busy boy.

[Tim Kurcz]

Now you're cooking with ice cold Avgas........ Gotta love the latent heat of evaporation!

[Mark75H]

Now you're cooking with ice cold Avgas........ Gotta love the latent heat of evaporation!

I'm an AC/Refrigeration mechanic ... I use latent heat of evaporation every day, this is actually about "sensible" heat. The latent heat of evaporation is unchanged.

Do you know the correct fuel height in a KA bowl for overflow set up? I'll probably be putting a stand pipe in from the bottom.

[proprider01us]

Hey Tim, if running this system on a 750 merc., what psi do you recommend for a set of KC carbs. Can I assume you keep the fuel tank vented? Thanks for all the insight.
Joe

[Tim Kurcz]

For KA's and KC's, I've never actually measured float height compared to fuel height - Bud explained that except for alky applications there was no need to free-flow Tillotsons. It stands to reason that you prime a KA or KC to inlet valve shut-off, then remove the top and float, that you should be pretty close. If you're too high it will eventually overflow the standpipe in rough water. Best idea is to make the pipes adjustable - or find an alky guy that has experience with them.

As for fuel pressure, conventional (floated) Tillotons always run well at 2-1/2 PSI. I've never run a return system because twin pumps feeding to center always get the job done.

According to Bud, stand pipe carbs always run lower pressures - the objective is to keep the bowl at a constant level regardless of RPM. Flow/bypass is more important than pressure. Again, you need to find an alky guy willing to share the knowledge.

[Mark75H]

It stands to reason that you prime a KA or KC to inlet valve shut-off, then remove the top and float, that you should be pretty close.

Thanks, that was plan A anyway ... was just hoping someone already knew. My guess would be that the level you see when you remove the top will be slightly lower than it was when the float was pushing the arms and needle up. Maybe I will measure the distance between the mating surface and the follower lever and push the float down to that level and use that fuel height as the over flow.

A return/overflow with a remote electric pump should let me pre-cool the fuel in the tank and have enough volume to keep the gas in the lines and bowls cool without a lot of bulky insulation. I have been concerned that with a regular Merc pump and lines to the carbs you would loose most of your cooling before the gas was used. It might even be possible to stuff the bowls and at the same time insulate the bowl and reduce the volume in the bowl that is not being used and potentially warming up.

[Tim Kurcz]

You've got it Sam. Lot's of flow through a cool can and you can pretty much ice down the intake system. I wouldn't bother with carb insulation - the venturi will take car of that. Just don't be surprised if you ice up carbs & crankcase if you run in humid air near 45F. At that temp, you might actually need warm fuel!

[Mark75H]

45 degrees on the water ... I need insulation:D

[Tim Kurcz]

Or might that be anti-freeze? LOL!!!

[850cc racer]

interesting how fred has his reg set up.. thats efi style isnt it?
how are you choking her fred? my choke set up is on the return side:cool:

i have raced over here in 8 degrees (45f).. yeh its a little cold :eek:

[sheuninck]

where do you get a cool can?

[850cc racer]

http://www.jegs.com/i/Mr-Gasket/720/1350/10002/-1?parentProductId=745113

i would be making something like that.. coil some aluminium hose/tube but i wouldnt have the holes as they are i'm going to make one with the fuel in the top and out the bottom like that one with it all sealed except the lid, then have a bung in the bottom to drain the water

[Mark75H]

Don't use hose ... it will not conduct the heat from the fuel. Best to use aluminum tubing heating contractors use for gas pilot lines.

Go to a heating supply wholesaler and ask for "3/8 aluminum pilot tubing"

[850cc racer]

aluminium hose/tube- i think thats the aussie slang coming into it.. i edited my post! :)

[Fast Fred]

last i knew, ya can't run a cool can in any class of SLT, so was not thinkin of that in my set up.

i choke her up with a squeeze bottle, like a Funny car, got to take the hood off,
no choke circuit on there, you should see the look on them couch boat peoples faces at the ramp:eek::confused::eek:;)

[Fast Fred]

Tim Kurcz, what is that right before the cool can, right after the pump?:cool:
and what is that at the top of the fuel rail? ( just after the carbs)

thanks
FF

[850cc racer]

thats the regulator. it goes- filter -pump -reulator.

then after the carbies is an orifice

[sheuninck]

last i knew, ya can't run a cool can in any class of SLT, so was not thinkin of that in my set up.

i choke her up with a squeeze bottle, like a Funny car, got to take the hood off,
no choke circuit on there, you should see the look on them couch boat peoples faces at the ramp:eek::confused::eek:;)

i did not see the rule against cool cans. i will take a look

[Fast Fred]

the rule book is short for Bandit and Outlaw, if it don't say you can, you can't.
it was talked about for "X" and voted down.

[850cc racer]

okay so its late here and i have a question:

Mr Kurcz has advised us he runs 16:1 oil.
Mr Fast has advised mod 50 book says 50:1

my question is: the life span i think i read fred saying 50 hours of WOT?

with more oil less friction does this make the engine live longer?

so 50hrs of WOT @ 50/1...

xx hrs at 16/1...

might be a dumb question but i want to ask.


850

[Fast Fred]

for me, just my .02, more oil make more of a mess. kind of oil makes more of a dif'
semi synthetic:eek:;):cool: at 25 to1 makes a mess all over her self.

[Powerabout]

more oil = less friction?
Less friction = less metal to metal contact
more oil = rings seal better
better ring seal = more power
( more power = finish race earlier so less engine hours)
more power = more heat/pressure?
more heat/pressure = ?

I am suprised the MOD 50 manual says 50:1?
every OMC race engine manual I have seen says 25:1
I think the evidence on this site and many other 2 stoke sites says there will be more power all the way rich till 16:1

[850cc racer]

Fred making a mess.. Mine made a mess when she had a weak spark on one. Changed that and she was all clean.

Has had a few idles on trailer no mess... Then a 'putt' on the river with too much fuel and no mess.

Powerabout: more heat i disagree with on avgas its keeping temp's down..
Did u get your housing?

[Powerabout]

Ya cant make more power without more combustion heat as thats what expands the gas more.
(all other things being equal)

I think the guys were talking that the latent heat of evaporation of avgas is better than petrol ( I dont know) so when it changes state from liquid to a gas it pulls in lots of energy, i.e. heat so therefore cools the air down for better volumetric efficiency so more fuel, more air, bigger bang, more heat, more expansion.

If you are running an engine on the dyno and the dew point is very low you can see ice forming in on the carbs especailly using methanol.
Remember carby heat on airplanes, lower air pressure lowers the boiling point of the fuel and the dew point.

Re Housing
Wifey banged herself up sailing on the weekend so is down for the count.
She will go tomorrow if she can, thanks for checking.
I am out of town at the moment.

Cheers

Powerabout

[Mark75H]

Latent heat of evaporation of AV gas is essentially the same as street gas