Fast Fred's Secrets of the OMC MOD50's Thread #1

[Fast Fred]

thanks, i likes it clean
http://aycu16.webshots.com/image/31695/2003012042462335009_rs.jpg (http://allyoucanupload.webshots.com/v/2003012042462335009)
http://aycu13.webshots.com/image/33332/2003078727902266904_rs.jpg (http://allyoucanupload.webshots.com/v/2003078727902266904)

[Fast Fred]

and the hood:eek:
http://aycu29.webshots.com/image/31228/2002922634636059331_rs.jpg (http://allyoucanupload.webshots.com/v/2002922634636059331)

[Detroit Whitey]

so where are you gonna sit with that huge tank in da way.Also just was wonderin how it turns right with that raNCHO on there?

[Fast Fred]

bum cheek right up against the gas can, keeps me off the transom. the Rancho
shrinks up for full hard over port and or starboard, starboard bein a long way cuzz of the bend a way tilla:eek: but i'm use to it, been runnin like that for about 10yrs.;)

[Fast Fred]

Oh, best tell Lauer he needs Mo duck tape on his doors, cuzz I'm a F'n showin UP!:eek: :cool:

[Fast Fred]

that gas can is only guna keep it lit for about an hour at WOT:cool:

[deejaycee_2000]

how many litres is that gas tank .... I need one of those .....

[Fast Fred]

?, 12 US gals.. thinkin thats about 48 liters. my metric liquid messurein is not all that.:cool: should keep your hibread 50hp lit for about 2 hours:cool:

[deejaycee_2000]

I want one of those, what brand is where can one find one online?

[Fast Fred]

tempo:cool:

[Fast Fred]

well then, someone was askin how ya put finger ports in a moda ya don't got no map for. no one showed me how, i just do it the way i do, it works. thare may be a different way, but i like my way and i'll tell yas how, Cuzz i, me, Fred want you to be fast, all of yas, so when i go Rippin by yas ,i'll know i'm doin somethin
for real, cuzz any thing else is crap:eek::cool:

so check back;)

[Fast Fred]

anyway, finger ports, why finger ports, well the dif' between a 150hp and a 200hp for the most part is, ya finger ports ,so we'll take them.
machined finger ports are vary nice, done by hand they can be every bit as nice. most important is the rings, we don't want to upset the rings. it's easyer to cut them(ports) before the rebore, that way you can clean up any slip ups you mite make. you want the ring gap to run about dead center in the finger port. or on the bridge of cyl wall in between the intake ports.
take the piston and mark the ring gap pins to the top on the dome, then put the piston on the rod, with no rings on it, bolt it to the crank, mark the cyl on top ware the pins sit, then at BDC make a mark.

i'll make some shots so yas can see it this far, then i move onto whats next.:cool:

[Fast Fred]

:cool::eek::cool:

[DKL]

Theres Mod 50 carbs and other parts on ebay right now!!:)

[Fast Fred]

lookin like them are just carb hulls, all the good stuff been pulled off them, the right parts are not easy to find, be hard to put them back in runnin order:cool:

[Fast Fred]

ok, cookin up some shots on the finger port demo, and some other related stuff,
see how they look:cool:

[Roy Hodges]

the "rubber ducky" , here in california (northern) holds the 2 man runabout world's kilo record at 112 mph. With only (if i have it right) a Rossi 350 C C motor. As far as i know ,this is the the fastest outboard runabout , regardless of engine size . (2 man ) - Driver- owner Terry Klemm.
(this refers to #258 )

[David Mason]

the "rubber ducky" , here in california (northern) holds the 2 man runabout world's kilo record at 112 mph. With only (if i have it right) a Rossi 350 C C motor. As far as i know ,this is the the fastest outboard runabout , regardless of engine size . (2 man ) - Driver- owner Terry Klemm.
(this refers to #258 )

Terry was using a Rossi 700CC or so engine. Sort of a custom I believe. I looked it over real good at DePue this year because he was pitted right next to me. Very Cool rig. At least the engine he had at DePue 2007 Pro Nat's was not 350CC.

[Roy Hodges]

Terry was using a Rossi 700CC or so engine. Sort of a custom I believe. I looked it over real good at DePue this year because he was pitted right next to me. Very Cool rig. At least the engine he had at DePue 2007 Pro Nat's was not 350CC............................................. .................................. Sorry, you're WRONG. I was there that day, last year, and talked to him . He told me , or , like you , i would not have thought it possible with such a small motor . So , unless i was told a LIE, it was that really small motor . For me , it's hard to believe anybody went that fast IN A runabout , with ANY SIZE motor . But, the clocks don't lie .

[Detroit Whitey]

I want to know what boat he was using? was it a v or a tunnel

[Jeff Akers]

It is neather a tunnel or a V.....Just a little flat bottom..This picture may be of an older one of his, but it should give you an idea of what the boat looks like:cool: (it was all I could find for now)

[Roy Hodges]

It is neather a tunnel or a V.....Just a little flat bottom..This picture may be of an older one of his, but it should give you an idea of what the boat looks like:cool: (it was all I could find for now)................
.................................................. .................................................. ................................... Now , everybody should know that in outboard runabouts , they ALL have to be flat bottoms. (O P C ,not included. ) We're talkin stock, modified, & "PRO". What's that old saying ? "A picture is worth a thousand words ? "

[Roy Hodges]

................
.................................................. .................................................. ................................... Now , everybody should know that in outboard runabouts , they ALL have to be flat bottoms. (O P C ,not included. ) We're talkin stock, modified, & "PRO". What's that old saying ? "A picture is worth a thousand words ? ".................................
.................................................. .................................................. ..................................IT WAS JUST BROUGHT TO MY ATTENTION THAT i SAID , LAST YEAR, that TERRY USED A....600 ROSSI . iN MY OWN WORDS. Yeh, who stole my memory ? Or did i lose it in a crap game .? anyways, even 36 cubes going THAT fast is mind boggling ! In a runabout . wotta yuh 'spect from an ole duffer 68 yrs. old ?

[Detroit Whitey]

yep! thats crusin:D

[Tim Chance]

.................................
.................................................. .................................................. ..................................IT WAS JUST BROUGHT TO MY ATTENTION THAT i SAID , LAST YEAR, that TERRY USED A....600 ROSSI . iN MY OWN WORDS. Yeh, who stole my memory ? Or did i lose it in a crap game .? anyways, even 36 cubes going THAT fast is mind boggling ! In a runabout . wotta yuh 'spect from an ole duffer 68 yrs. old ?

That's right 36 c.i. in other words a bored out "C".

[David_L6]

That's right 36 c.i. in other words a bored out "C".


Closer to a D than a C. ;) Still, very fast for the size of the motor.

Here's another picture of that boat going very fast. :cool:

[David Mason]

.................................
.................................................. .................................................. ..................................IT WAS JUST BROUGHT TO MY ATTENTION THAT i SAID , LAST YEAR, that TERRY USED A....600 ROSSI . iN MY OWN WORDS. Yeh, who stole my memory ? Or did i lose it in a crap game .? anyways, even 36 cubes going THAT fast is mind boggling ! In a runabout . wotta yuh 'spect from an ole duffer 68 yrs. old ?

I knew it wasn't a 350...

And to boot, Terry is a pretty likable fella. Takes some large cahonies to run that fast in a runabout with two people in it !! All I know is that man works hard and earns his titles. He worked non stop on it to get it ready for his heat as he flew in and Rick Bird brought the boat and engine. Terry had to rig it, and all that.

[Roy Hodges]

Think about this . He drove , over 30 years ago, Mike Snell's "Midnight oil" . An
"R" hydro, ( a Ron Jones cab over ) with hopped up Merc 800 (4cyl.) it held the R kilo record at about 107 mph . This flat bottom , with 30 LESS cubes went 5 mph FASTER , with another (extra) guy on board ! Yes, Terry is a nice guy . I remember talking to him backin about 1975 at Stockton, and telling him about another driver who said he was gonna run over him , Terry just smiled and said " He's gotta catch me first !"

[Fast Fred]

ok, gots me a new camra :eek:, i wasn't gettin the shots we needed so ya can see it. so hang in:cool:

[Fast Fred]

workin the new camera, maybe a vid soon, see how that goes:eek::cool:
gots this one on deck, made a new water cover for the head, so i could move the water dump, gots the bigger carbs on this one;), this is what i'm startin the season with. hows my run on sentence?:eek:
http://aycu07.webshots.com/image/48566/2000001103147023397_rs.jpg (http://allyoucanupload.webshots.com/v/2000001103147023397)

[Fast Fred]

this power head, previously shown, has been sold.
http://aycu20.webshots.com/image/42579/2001186708026637574_rs.jpg (http://allyoucanupload.webshots.com/v/2001186708026637574)
:eek::cool: thare is another, to back this one up.:eek:

[Mark75H]

Did it go to another guy racing in your class?

[Fast Fred]

it's on a Drag boat, guys in my class feel 56 cubes will save them, or 999cc of Yamaha with nic bore. if need be i'll melt it it to a blob of slag for the win,i don't think that will be necessary :eek:

[Detroit Whitey]

These little motors are not the answer for X class but they are better in the mod classes.they just dont have the ball`s even with 2brl carb set up.You just show up there fred and we`ll see about the 49 vs 56 i can tell ya it`s not gonna keep up even if ya paddle as fast as ya can.

[Fast Fred]

Yup, Yup..... the Merc guys said the same, Hey not like thares any chance i'll pull out a long rod 58 incher with an M31 front 1/2 on it:eek: ya no chance of that:eek::eek::eek:;):cool:

[Ron Hill]

Fred can you tell me the year by looking at the water pick ups???

What cubic inch are these three holers???

[Fast Fred]

i gots a 55hp with them pickups, it's the big foot, it's like 2.50 to 1, ski foot or works good to like 800ft at the Drags.:eek: early to mid 70tys, showin it in the 74 and 75 service manuals, they refer to it as a 20" transom LU:cool:

[Fast Fred]

i did hear from Drag boat guy, the owner of said Mod50 power head, he did mention in no uncertain terms Mark75h, that he would be willin to leave you in his wake usein said power head:eek::cool:

[Mark75H]

i did hear from Drag boat guy, the owner of said Mod50 power head, he did mention in no uncertain terms Mark75h, that he would be willin to leave you in his wake usein said power head:eek::cool:

It will be interesting to hear how fast it runs on his boat :D

[Fast Fred]

last i knew, it was about 82+:cool:

[Mark75H]

last i knew, it was about 82+:cool:

cool

[kamikaze]

Hi Fast Fred,

I am new to the forum, I have sent you a PM, but it said your inbox is full, and my msg can't get thru,

Regards
Dave :eek::eek:

[Fast Fred]

i sent an email to ya:cool:



Mark75H
Quote:
Originally Posted by Fast Fred View Post
last i knew, it was about 82+
cool

just Moda:eek::cool:

[kamikaze]

Hi,

I'm not sure if you can get them for a OMC 3cyl, but Just wonder if anyone has used velocity stacks on the 3x2 barrel carb setup?

And if they made an improvement to performance ?

Regards
Dave

[Fast Fred]

no help, hurts it, pulls to much gas at the top, put them on the crossflow:cool:
http://aycu36.webshots.com/image/47235/2005182882608463691_rs.jpg (http://allyoucanupload.webshots.com/v/2005182882608463691)

[kamikaze]

Thanks for your reply Fred,

I thought it may flow air better, hence some improvement in performance

They look neat, is that a custom made set, or can you buy them like that?

Regards
Dave

[Fast Fred]

them is cross flow stacks by Land and Sea, don't think they make them any more, took about a year to find them. they will just slow ya down on the Mod50,
you want the 1 3/8 carbs.:cool:

[kamikaze]

I did a search,
http://www.land-and-sea.com/marine/velocity%5Fstacks.htm

That was all they had on their website

I sent you some pics via email Fred,

Regards
Dave

[Roy Hodges]

no help, hurts it, pulls to much gas at the top, put them on the crossflow:cool:
http://aycu36.webshots.com/image/47235/2005182882608463691_rs.jpg (http://allyoucanupload.webshots.com/v/2005182882608463691)
.................................................. .................................................. ................................. .Is this a "tuned exhaust system? " The 65-75 horse fishing motors was tuned , but this exhaust looks like the old 55-60 horse motors .I've heard some racers say "oh, tuning doesn't matter" . ! If not, why did O M C go to such lengths tuning those motors ?

[kamikaze]

Can you get decal sets for theses engine covers?, either Johnson stinger, or Johnson/Evinrude SST

What is available ???

Thanks
Dave :D:D:D

[Fast Fred]

Dave over at Sea-way in wa. most likely gots some. :cool:

[kamikaze]

Thanks Fred

Been trying to email you a few times now with some pics, but it keeps coming back

Thanks Dave

[Fast Fred]

(tboats@comcast.net)%$&*:cool:

[kamikaze]

Thanks Fred,

I'll get it some pics off to you again
:D:D:D:D:D

Regards
Dave

[Fast Fred]

you got a 56 with a 19s front 1/2, big torque, but will not peak like the 49, it's in the geometry of that moda. talked to a factory OMC mod50 builder, he said
no mater what thay did to the 56 the 49 allways made more HP, and that they did eveything,:eek: on a short course should be the Bomb:cool:

[kamikaze]

Thanks Fred,

I don't have much ( make that no info) info on them, I did down load a parts file for the SST-60 off the sea-way website, I understand it is a bit different to my engine, just help give me an idea, , I emailed them about the decals too

So is my engine a bitsa....(bits of this, and bits off that) a 56 ci with an 19s front?

Regards
Dave

[Fast Fred]

Best Bista, all the best bits ;)

[Fast Fred]

Hay kamikaze, a shot of a cyl with the piston at BDC, would be good.:cool:

compression, octane and timein relate, you must have enough octane to suport
said compression, or timein has to go down:cool: or it Burns down.:eek:
at 145-150psi ya got to backoff the timein on pumpgas , thinkin thats about 28-29cc head.

Hay 850, how did ya do:cool:

Exhaust SO does Matter, :eek: oh ya:cool:

[Droll-l6]

ok, cookin up some shots on the finger port demo, and some other related stuff,
see how they look:cool:
Still waiting for the follow up :)

Arne Kjetil

[Boatnut]

hey fred, MORE:D:D:cool:

[Fast Fred]

ok, take your pistons ( it's easyer to finger port the cyl before you bore it when
doin it by hand, make sure pin location is the same on new piston, the new bore
job will clean it up) old ones, after checkin pin location, and mark as shown:cool:.
http://aycu24.webshots.com/image/47343/2001120657342480230_rs.jpg (http://allyoucanupload.webshots.com/v/2001120657342480230)
http://aycu04.webshots.com/image/49923/2001168436068069837_rs.jpg (http://allyoucanupload.webshots.com/v/2001168436068069837)

[Fast Fred]

more like the one on the right side, take your time, get it lined up nice nice.:cool:
then reload on the rod, full deal, ( cee clips, you want them like the letter C, if thay have tails, cut them off, but not short):cool:
no rings
http://aycu14.webshots.com/image/47453/2001145597946018305_rs.jpg (http://allyoucanupload.webshots.com/v/2001145597946018305)

[Fast Fred]

i'll shoot some more tommrow, every body with me this far ?:cool:

[Fastjeff57]

Read through all 32 pages and saved nearly every photo. (I and am at the bottom of the learning curve on these motors.)

A (dumb) question or two:

1. Did the 56 cubers come with two barrel carbs, and is that what constitutes a 70 hp engine?

2. What is the approximate weight of a 49 cube power head?

3. What is the driveshaft like (diameter, number of splines, etc.)?

Thanks,

Jeff the Learner

[Mark75H]

The powerhead weighs approximately 110 pounds without the flywheel (a little more than my 60ci inline 6)

I'd have to go down stairs and measure a driveshaft end, maybe take a pic to make it clearer

[Mark75H]

The driveshaft is about 5/8

The top of the driveshaft looks like this, 4 shallow splines

[Fastjeff57]

Yikes! It's a porker! My back would not allow me to tote that monster around, so... Back to the Merc 500, I guess. (It weighs 130 lbs, complete--heavy but managable.)

Thanks again,

Jeff

[Fast Fred]

they did try at the factory on the 56, mod 50 front 1/2, long rods, finger ports , the works. it never made as much Power as the 49 cuber.
ya 110lbs seems about right,:cool:

[Fast Fred]

ok, so then ya want to put the crank in, ever so nicely set it in, ketch the three pins,
http://aycu14.webshots.com/image/50893/2001575238440565359_rs.jpg (http://allyoucanupload.webshots.com/v/2001575238440565359)

[Fast Fred]

and check to see that she is lined up,
hear like so,
http://aycu15.webshots.com/image/48894/2004399955243727833_rs.jpg (http://allyoucanupload.webshots.com/v/2004399955243727833)
seated hear
http://aycu11.webshots.com/image/49850/2004381062379170122_rs.jpg (http://allyoucanupload.webshots.com/v/2004381062379170122)
and hear
http://aycu05.webshots.com/image/47804/2004384388881268428_rs.jpg (http://allyoucanupload.webshots.com/v/2004384388881268428)
she should spin like butter:eek::cool:

[Fast Fred]

and then, so ya don't have to mess up the crank, we jackitup, like so
http://aycu40.webshots.com/image/49599/2006395563911761337_rs.jpg (http://allyoucanupload.webshots.com/v/2006395563911761337)


then with NO rings ya get your three bullets, to entertain my self usein these hear:eek:
http://aycu04.webshots.com/image/48083/2001425291352666543_rs.jpg (http://allyoucanupload.webshots.com/v/2001425291352666543)

[Fast Fred]

and load them
http://aycu29.webshots.com/image/51228/2000434776228919617_rs.jpg (http://allyoucanupload.webshots.com/v/2000434776228919617)
http://aycu34.webshots.com/image/48353/2004259917657641798_rs.jpg (http://allyoucanupload.webshots.com/v/2004259917657641798)





;):cool:

[Fast Fred]

ok, thinkin we need some more shots:cool:

[Fast Fred]

this is pretty cool:eek:, Merc powered.
http://www.youtube.com/v/4qVMRH5gnyQ&hl=en

[Fast Fred]

the boat and driver , Spencerized16, :cool:

[Boatnut]

I'm not known for being too bright but is that two different pistons and three different rods you have just installed in the block????:eek::cool:

[Fast Fred]

all 3 pistons are dif', not a lot, the locator pins are in a dif' spots on each piston.
so we can see it a bunch a ways, on how to go about makin it work in what u got.:cool:

[850cc racer]

fred!! long time no talk, i did email u? not sure if u got it, last week i bought some stuff, 920cc "ft" front its finger ported, has a wicked looking head on it.. its gonna have huge compression, ill take some photos and put up.. needing some advice!!
also amongst it was a 1120 yammie powerhead, has an adapter to run the omc ft carbs.. on a 15 inch omc mid with a twister "quick foot" mean looking bit of stuff..
ill snap photos.. have u changed email addresses?

[Roy Hodges]

all 3 pistons are dif', not a lot, the locator pins are in a dif' spots on each piston.
so we can see it a bunch a ways, on how to go about makin it work in what u got.:cool:........................................ .................................................. .............
.................................................. .................................................. ................................. Is that just for illustration, or.... are you going to run all those different parts at one time in the same motor ?

[Jeff Akers]

.................................................. .................................................. ...
.................................................. .................................................. ................................. Is that just for illustration, or.... are you going to run all those different parts at one time in the same motor ?


Roy, I think I can safely say that Fred is using the three different pistons/rods in the pictures to show the different combinations this engine can be configured to, and what modifications will be needed for each one to work properly...Each one has it's advantages / disadvantages........ (Since this is Fred's thread, I think I'll let him explain the rest,as he is doing such a great job) :cool:

[Fast Fred]

ya that just for lookin, don't think it would run to Hot, be bustin somethin up in short time.

Hey 850,
ya still the same, workin at the Local marine, long days, ya would like to see that Mod50 lookin Yamaha 90hp with the Merc drive:eek::eek::cool::cool:
puttin on a Fresh Mod 50 power head right now:eek: ya it's All good:cool:

[Fast Fred]

ok, see what this looks like
http://img2.freeimagehosting.net/uploads/601ebe44b7.jpg (http://www.freeimagehosting.net/)

[Fast Fred]

ok the narrow rod is in the top or number one hole,big A-frame rod in number two, middle,, Mod50 rod in number 3 hole, bottom. ( see last page)

[Fast Fred]

from the Top, number one.:eek::cool:
http://img2.freeimagehosting.net/uploads/03f26895ed.jpg (http://www.freeimagehosting.net/)
http://img2.freeimagehosting.net/uploads/1810dc8ec5.jpg (http://www.freeimagehosting.net/)

[Fast Fred]

finger ports are in this one already, at 19-s Mod50 spec, just roughed out,
she was over OVER bored on me:(:confused::rolleyes:, any who, she will work well for this DEMO:cool:;) so lookin at ware them pins line up, Ya, it's guna work with them OLD style narrow rods and Bullets, finger ports need to be touched up for best turn out but way workable

[Fast Fred]

hole number 2, center, got the newer A-frame rod, pins on this piston are at ( exhaust port center bein 12 O'clock,) one pin is at about 9 O'clock the other at about 4 O'clock . this would Work,
http://img2.freeimagehosting.net/uploads/de36b46f24.jpg (http://www.freeimagehosting.net/)

[Fast Fred]

:cool::eek:
http://img2.freeimagehosting.net/uploads/82125f0367.jpg (http://www.freeimagehosting.net/)

[Fast Fred]

on the last or bottom hole with the Mod 50 rod and bullet just guna have it TOP pined on the pencil Mark.

[Boatnut]

So the idea is to make sure the pins and ring gap runs up and down over a consistant surface and not over the edge of tha ports?? Am i on tha right track?????:)

[Fast Fred]

yes, you don't want to upset the rings. the gap has to ride on the wall or some what centered in the port. half on the wall and half in the port will never last:eek:, it will just kill it's self in about a hand full of pulls:cool::cool:
you want it so the rings and the piston kinda don't even know the ports are thare, thats guna stay together, ;)

[Fast Fred]

http://img2.freeimagehosting.net/uploads/a70d5cc43d.jpg (http://www.freeimagehosting.net/)

[Fast Fred]

on the left we gots a SST60 style Lostfome case, on the right gots a sandmold
56cube case.:cool:

[Fast Fred]

and spin:eek::cool:
http://img2.freeimagehosting.net/uploads/352e5ebc91.jpg (http://www.freeimagehosting.net/)

[Fast Fred]

and spin some more:eek::cool:
http://img2.freeimagehosting.net/uploads/56d756aca0.jpg (http://www.freeimagehosting.net/)

[John (Taylor) Gabrowski]

I am planning making up a 4 carbs in a row for a Merc 44 with left over OMC 3 holer carbs dumping into pyramidal reeds system. All these carbs have fixed jets. Does anyone have any experience converting them to high speed needle adjustment?

[Fast Fred]

? spose ya could pull the main jet out and make it into a seat, then use a needle
screw in place of the drain plug:cool: that should do it for ya.:cool:

[John (Taylor) Gabrowski]

Thanks Fred: Last year I purchased a new 3 Holer 49 cube OMC long block at a garage sale for $200.00 and it came with lots of extras from another one that wore out, so I made up that 3 holer for racing SE but with it I left the carbs intact with fixed jets. Since I landed a 4 carb specialty case for Merc 4 cylinder where 4 carbs could be mounted and hearing that these carbs might be tuned better with a high speed needle came the notion I sould ask because I have no experience with these OMC carbs at all other than from people using them on B1s and trying them out on the OMC 35s. Thanks for the advice, I will sure look at that real hard now. :)

[Boatnut]

Only seein a few differences between the cases, is one better than the other?

[Fast Fred]

Boatnut is one better than the other?

not sure, the solid mold is nice and smooth in the ports, No glue lines, seems that it moves more water through the case, lookin at divider. :cool:

[kamikaze]

Hey Fred,

Just outta interest, does the V4 OMC powerhead fit on the stinger mid and gearcase, Been told it will,

I dunno, new to OMC.......hhhmmmm... and outboards:D:D:D

[BRIAN HENDRICK]

This SELVA 850 for sale on a German web site
Some resemblance to a Mod50
What are they derived from?

[Mark75H]

The Selva race motors are based on the Selva fishing motors. Selvas are their own creation, no direct forbearers. By coincidence, Selva started just after Carniti closed up; so it is possible that some of the Carniti engineers may have been looking for jobs when Selva was starting up.

Carniti had triples and prototype 6's that looked amazingly like T-2 Mercs ... before Merc built the T-2's.

[Fast Fred]

at a glance, not lookin like that v-4 powerhead is just guna jump on thare.
but then i did see a v-8 on a merc OS mid and drive:eek:, a 20" 3cyl mid is lookin a lot like a V-4 mid, exhaust addapter for sure got to change.

cool :cool:a 50cuber F3 SELVA, lookin like port side exhaust, and OMC carbs:eek:

:cool:

[NERSTROM]

The carbs in the picture are OMC, for some reason Selva was never able to make their carbs work and would buy OMC Mod50 carbs for their engines. When Paul Kalb got wind of this he put a stop to the sales.

[Lars Strom]

The carbs in the picture are OMC, for some reason Selva was never able to make their carbs work and would buy OMC Mod50 carbs for their engines. When Paul Kalb got wind of this he put a stop to the sales.

Hi Jim,

I remember that, to bad for Selva.
The OMC carbs was the only good
thing with that engine!!!

I think the Mod 50-OE-F3 was the best class in Racing with
"production style outboards"
and my best Racing memories is from that class

Thanks Jim for all the good work you did at OMC.

PS. I think they still used OMC carbs for years

[Roy Hodges]

The carbs in the picture are OMC, for some reason Selva was never able to make their carbs work and would buy OMC Mod50 carbs for their engines. When Paul Kalb got wind of this he put a stop to the sales....................
.................................................. .................................................. .................................
It seems to me that they could just have used regular V-4 cabs. Tom Ireland used V-4 carbs on his mod 50 . At the 1976 opc Nats, he said he was using 100 horse cabs , and was going to try the 140 horse carbs .

[Fast Fred]

the main nozzel is too big in diameter on the stock carbs, it Will flow too much fuel.;):cool:

[Lars Strom]

There was plenty of those OMC carbs around in Europe, and I think the Selva brothers just bought them
from a dealer or Ital-Marine as a carb for the FT 19 S SE engine.

I sold many FT 19 S to race drivers as a dealer, and if I remember right OMC Sweden stocked that model
1978-79.

[Fast Fred]

i gots the next power head, called a striate in, guna make a bracket for the shifter. thares a shot of it on like page 2 of this tred.;)

[Fast Fred]

hey Sheuninck Ron hill mite have a Nitro for ya, a prop, a 21p would be about the best, could try the SST60 guys, but don't over pay, Titus in Fl makes them but you gots to pay the big coins, like 800 or so. i may have a suit.:cool:

[Fast Fred]

tryin for a clip of film, see how it goes.:cool:

[Fast Fred]

need some help, think my fuel psi is to high, she washes out the plugs, i mean like swimmin in fuel. talked to Dave at Sea-way in the book for F3 carbs fuel psi
is 2.5-5.5psi . the jets are not to rich, don't seem like she can handle that kinda psi. any body got the float hight for the 1" 2bbls 19s FT carbs?
thanks
FF


did get it to Turn On a Bit, once or twice, ya FT tiller you so gots to get some:eek::eek::eek::):cool:

[Fast Fred]

ok, on the dyno they said some thing about they was pushing the fuel,thinkin the pump they was runnin did not have enough volume to feed it, so they moved the floats on thses carbs, ya i remember them sayin that. made a float adjustment, :cool:

[Detroit Whitey]

sounds like ya got the wrong reglator it took me awhile to find one that went down to 0 and back up a bit.you might also look at the float drop and not just the height but hek im not tell you any thing you dont know Phantom fred!!!!!! no top o again FOS!!!:cool:

[Fast Fred]

i was tryin, took the time off, it wasn't comin together on a co-pilot. see about workin the co-pilot thing out now, next year think the Deanster will be lookin to run his new hull too at the Top O'. so tell me how did it go, Who won, Who Roasted:eek::eek::cool:

i remember Mr W. sayin that he was pushing the fuel and that they moved the floats. think that he did not have enough volume on the pump he was runnin,??

[sheuninck]

http://gallery.me.com/mcvideo#100008&view=null&bgcolor=black&sel=245

[Fast Fred]

can't seem to get that to fire up,?

[sheuninck]

http://gallery.me.com/mcvideo

[Fast Fred]

hay 850, have a good day:cool:

[Powerabout]

Fred
Do you have a photo of a stock cyl head and a Mod 50?
Some of the photos of the pistons in earlier posts are flat top and some have a slight dome, were the heads altered to suit this?
Regards
Powerabout

[Fast Fred]

page 16, thare is a factory 19s head. i'm runnin flat top bullets so the squish band needed is not the same. runnin a tricked stock head, found it on a shelf in like New Jersey or some place over that way.

[Fast Fred]

a peak at some other related stuff.:cool:

[David_L6]

Fred,

Are any of the motors you've built being raced in APBA Formula E class?

[Fast Fred]

they all would be considered Cheater Modas in that class.

gots one i'm buildin, SST60SIXPACK:eek:

not only would you get DQed you would be Band:eek:

stock bore wiscos :cool:

[Fast Fred]

Hey JT you out thare, have a good B-day man, i hear thares a Fast Fred Mod50
out that way with Yamaha 3 ram tilt and trim:eek::cool:
thanks for your help on stuff:cool:
lookin for an adapter for ya:cool:
hears a shot of them stairs, a first place and a last place trophy:eek::cool:

[Fast Fred]

open house on sunday, had to pull down my power Mantle, but i took a shot first. i pulled this one outa the woods, tricked it up and mounted it.:cool:

[Mark75H]

Fred the only ones of yours I've seen that would be illegal 850/SuperE are the ones with 2 barrel carbs. The only thing someone would be banned for is illegal fuel ... the carbs are just DQ's

Maybe you should look at the rules

[Powerabout]

That bridge port is a bit wide?
What do ya think?

Powerabout

[Fast Fred]

looks like could have gone wider, but lookin good right thare;):cool:

ya be best to see them rules, finger ports? wiseco's? twisted port map:eek:?

[Powerabout]

Fred

I meant, I thought the bridge was very wide?

Powerabout

[Fast Fred]

Hay J.T., you out thare, gots that adapter you were lookin for.
seen some biger than 90hp carbs:eek::eek:, i'm not sure thay will stack up on the 90hp intake, cuzz thay are so big they may not fit. for sure have to make a new intake.
they are off a 250hp Yamaha:eek: so i'm thinkin they will feed 125-150hp.
gots an intake and some carbs to mess with, see what i can see:cool:

[Fast Fred]

i'll say some stuff about the bridge, right now getin me some food.:cool::eek:

[inshoreracing]

Hi,
where have you find the selva engine in germany?

regards
jm

This SELVA 850 for sale on a German web site
Some resemblance to a Mod50
What are they derived from?

[Fast Fred]

i'm not sure ware BRIAN HENDRICK saw that moda, maybe he will tell us.:cool:

on the bridge, ya you can thin it out, but then it kinda looses it's power to cool it's self, and runs at a hotter temp witch makes it grow and come into the cylinder , so you have to push it out of the cylinder .002 thou., then you get to line up the oiler holes on the thin bridge, it will get thiner but not by much.
hows my run on sentence, it's got to be a good one.:eek:
pushin it to the out side, the port, and that will help it stay together with the sorta stock width bridge, :eek::eek::cool: i'll flash another shot once i tune on it some more:cool:

[quty06]

Hi Fast Fred,

interested with 70hp carb mods on pro50, can u share with us how do u fitted it.

thanks in advance

[Roy Hodges]

Hi Fast Fred,

interested with 70hp carb mods on pro50, can u share with us how do u fitted it.

thanks in advance........................................... ................................................
.................................................. .................................................. .................................
I have a question ; for Rapid Freddy - Have you ever given thought about a "rotary valve system " , like that on a Mc Culloch 590-630 for a 70-75 horse 3 banger omc ? it seems to me that removing all reeds & reed blocks would allow more air into the engine and be as good as the mod 50 reeds and carbs . I will not say that the McCulloch had a "true" rotary valve , but what ever you call it , I think it was a good thing, especially in an engine with a reputation of breaking reeds

[Sam La Banco]

There was an experimental rotor valve 3-cyl motor built in engineering at OMC when I was there. I'm not sure it was an "offical" project at the time though.

Because I don't remember if it was an "offical" project or not, I can't name the engineer that built it, and I'm not sure how much power it made. I do know it had to be pitched out of someones locker though.

[Roy Hodges]

There was an experimental rotor valve 3-cyl motor built in engineering at OMC when I was there. I'm not sure it was an "offical" project at the time though.

Because I don't remember if it was an "offical" project or not, I can't name the engineer that built it, and I'm not sure how much power it made. I do know it had to be pitched out of someones locker though............................................ ......................................
Thanks for your input . Very interesting . If anybody ELSE has any knowledge on that motor ,or the rotary valves , how they (might) work on the OMC 75 H.P. , I'd sure like to hear it .

[BRIAN HENDRICK]

[QUOTE=inshoreracing;62276]Hi,
where have you find the selva engine in germany?

Sorry, i can not find my reference to that site, although it is current. Looks like a commercial dealership, so maybe some one in Europe would know who it is.

If any one is seriously interested in acquiring a complete 19S, I have one gathering dust. I paid a lot for this motor , just so i could get a look inside one, when we were racing FEH.

[Mark75H]

I will not say that the McCulloch had a "true" rotary valve , but what ever you call it , I think it was a good thing, especially in an engine with a reputation of breaking reeds

The McCulloch rotors were "true" rotors much like the 1930's Johnsons ... rather than a disk or crankshaft passage rotor, they were externally mounted rotating barrels.

The fishing McCulloch made 75.2 hp. With bigger carbs, a different head with higher compression and better combustion chamber shape, higher porting and the rotors the 630 racing McCulloch made about 88.5 hp at 6,250 rpm instead of 5,200 rpm; so we know that the Mac gained less than 13 hp with by adding the rotor. Probably only 5 or 6 hp.

The thing that generally stops rotors from being big magic is that motors where they really made a big difference also had advanced transfer ports and expansion chambers. It was the whole package that Kaaden developed that made the difference. Remember, Hot Rods had rotors and were basically only peers to the 20H at the same motor size.

Just the same, I think it would be very interesting to see rotors on a 3 cylinder OMC.

If someone wants to know the internal structure details, let me know, they were actually pretty simple and could easily be made for the OMC.

[Detroit Whitey]

well lets see the internals i`ve been kicking this around for some time and even started to make one but lost the time to finish but i would like to see more

[850cc racer]

Hey there fred. its been aaaaages:confused: i have something trick to show you, gots me a 920 with ft front, and a trick head. ill take some photos in the next few days! no water goes back down through the midsection!:D

[Fast Fred]

cool, would like to see it.:cool:

[formeone]

haaa fred ...can you repost your port map seems a few of us cant down load/look at it ,,, still curious...

[Fastjeff57]

Disk valves really work efficiently only in a single cylinder motor--note the successful Kawasaki and Can Am dirt bikes of years ago. When cylinders are stacked one atop another, it requires an external barrel like the old racing Johnsons, and that kills the efficiency--long, dead air space in passages.

Jeff

[Mark75H]

Jeff, don't tell that to the thousands of racers who have driven disk valved 2, 3, 4, 6 and 8 cylinder König racing outboards.

The 4, 6 and 8 cylinders used an external disk, the stacked 2's & 3's used internal disks without the long dead air spaces. Konig also derived a 3 cylinder motor for Volvo with internal disks and no long dead air spaces.

The same designs were not used on motorcycles because it would have made the motors too wide with the power take off and clutch stacked on the side, not because it could not be done or didn't work good enough.

[Sam La Banco]

Great point SAM, the champ hot rod didn't do to bad of a job either.

By the way, in the mid 60ies there was a 2 cylinder bike with dual rotor valves
that was a rocket for their size. The BRIGSTONE 175 AND 350.

Both were killer fast.

[850cc racer]

okay so heres a 920cc head. me thinks someone has put some time into this one..:o


and some work to the block :eek: not gonna use this. it was meant to be "fully rebuilt" when i bought it, 2 pistons dont even have fingerports in them, and two have scores on them u cold grate cheese with!:mad:

[Bill Gohr]

While the Scott had what some people call "true" rotary valves, discs are too, any "valve" that rotates is one. While the Scott had the nice "add on" system it left alot of dead space behind it, if it was incorporated into the front half it would have been better.

And if you think that a disc is not as efficient, don't tell Rotax that they may disagree with you and their always successful bike and snowmobile engines, as, don't forget the Gamma, 500cc 4 cyl bike motor..................

[John (Taylor) Gabrowski]

Just looking at your Mod 50 as I have not done a thing to the new 49 incher 3 Holer SE motor that is stock yet, like your motor I am going to run into spots in the crankcase where there is a casting ridge, edge or something you would think would be smoothed out for better gas flow or is that not really nesessary? I got this thing a out any potential for a particle of aluminum to break free too. Its a kind of paranoia that worries that something small breaking loose can make a big mess.

A lot of 2 strokes for racing and pleasure have the bell shaped heads. Some use offset squish to one side into combustion chamber proper to make the charge very turbulent before ignition. How do the designers determine what makes the best combustion chamber for what kind of loop charged engine. Is there some kind of set of rules governing a given overall engine design or??

[Mark75H]

How do the designers determine what makes the best combustion chamber for what kind of loop charged engine. Is there some kind of set of rules governing a given overall engine design or??

No there is no rule ... just like props ... test, test and test some more

[John (Taylor) Gabrowski]

Mark 75H:

That is too simplistic an answer no one can really accept. When putting together an NOS complete class B 348cc stock racing British Anzani, its original head installed at the factory was bell shaped no different than the OMC in basic design. The Alky head on the Anzani though is different with offset combustion chambers just like that copied in principle later by Quincy Flatheads. There must be engineering motivations to make those kinds of choices and decisions when engineering any kind of 2 stroke loop charged engine? I am sure testing over and over again with design variants helps prove designs but there must have been some very basic technical rules involved that helped to make decisions and not just but also included hunches?

Anyone else have some more insight? There are serious engineering concerns here at play.

[Mark75H]

There are squish band considerations that can be used to arrive at the best turbulence and spark plug placement guesses to reduce overheating of the piston.

These issues are all covered in the standard texts for 2 stroke design: Gordon Jennings' Two Stroke Tuner's Handbook, etc ... but they all come back saying there is no substitute for testing ... as many configurations that seem to be "right according to theory" are just plain wrong for any particular motor.

[Fast Fred]

hey 850,
nice finger ports, the blending work looks good as well. that head is nice, who made it? what happened, can't see the cyl' walls good, looks like a hone and reload with fresh rings from hear.:cool:

i'll put up that map, tell me if you can see it .

[Sam La Banco]

John if it were me, I would start with the high compression factory head dimensions. Stop development at that point, and measure cc of combustion chamber and squish band dimensions. Run the motor, Optimize timming, jetting
and record running temp.

Then I would say your ready to start a development program. (if you want to do it with the sound engineering princples you mentioned).

As Sam said, then it's all testing after that,.......... well except for a whole lot of compromise between motor survial and power.

The Jennings book is an excellent ref. on the subject.

[Fast Fred]

i would want to see how the rotary valve set up worked on the outboard. no clutch, sleds gots a clutch, bike ya it's got one too. was a dude that ran a Rotax, i think, i was not thare, but any way i was told it did not have the torque it need low end.:cool:

i'm feelin ok about sayin that it's not guna make a gain in hp that would make it worth all the work.:eek:

[Fast Fred]

the more meat you take out of the crank case the lower the transfer psi.:cool:

[Bill Gohr]

You're not gonna start about squish area's, ratio's, and angles are you? Too many variables to relate to to make a "blanket" statement regarding this topic, and if there was a given "standard" alot of engineers would be out of a job. Read the Jennings book it will either make you think or totally confuse you, you can try numerous configurations on the same engine and 2 or 3 out of 6 will have the same outcome, which is correct????????????

[John (Taylor) Gabrowski]

The interesting thing about looking at engines with 2 types of heads is evident and that is from the late 1950s and into the 1960s. Some took the Anzani bell bead and machined it down to where it could produce high compression for Alky racing. Some used the gasoline bell head to use more nitro in the methanol fuel. Still others made the high compression Alky head higher compression still and still put more nitro in the fuel cutting back ignition timing to get power another way. All that took a lot of configuring way back then by some real knowlegable people. What were they thinking?

Back to the OMCs, to make them cooler other than ditching thermostats if present what other cooling tricks can be used to specifically cool them down and keep them that way? Any old Deflector Alky Merc tricks of any use?

[Bill Van Steenwyk]

Fred:

I have read many of your posts about the 3 cyl OMC and other engines you have worked on with much interest. You seem to have the knowledge and capability of doing a lot, if not most of your own work, and don't have to depend on second hand info to find results. I enjoy your posts and pictures, and hope you continue with them.

Regards your comments about rotary valves: Since the late 60's until his death Dieter Konig built a large number of disk type rotary valve engines that for a 25 year plus period were the dominant engine in the "alky" racing community. His basic design with porting improvements is still manufactured today and marketed under the "Konny" brand. If you would use the word "Konig" on the search function of this site, you would find much information that would probably keep you busy reading for several weeks. These engines used neither clutch nor gearbox, merely the same type of lower unit used by many other outboard racing engines, one single gear ratio. Wayne Baldwins thread on this site entitled "An Amazing Story" has many stories about the Konig engines and their performance. I understand your thoughts about narrow powerbands, but the Konig rotary valve "cut" was such, along with porting, that overcame a lot of those obstacles. Along with that was the way the motor was designed, i.e, two cylinders firing together to enhance the torque of the engine. I am sure you would find their design interesting. They were made in quite a few different displacements, from 250CC up to 1000CC and 3, 4, 6, and 8 cylinder. There was even a 12 cyl designed, but I don't know whether it was ever built. There were also a large number of 2 cyl's built, but to my knowledge all those were reed valve. The other models must have been built in the hundreds as far as quantity was concerned.

Regards your comment about crankcase volume versus pressure:

I think I understand you to mean the tighter the crankcase volume, the more pressure to force fresh fuel/air mixture into the combustion chamber. This has always been "conventional wisdom" but their are some cases where more is not always better, in the case of an engine restricted carb venturi wise for example. For more info in this you can also see some of John Taylors threads where posts relating how increasing the crankcase volume increased the performance of the engine.

Theory is great, but nothing beats "doing it" and then putting it on the boat and testing. I am sure you have experienced this yourself. As I mentioned, I really enjoy your posts and pictures. Hope you are able to continue.

[Bill Gohr]

Back to the OMCs, to make them cooler other than ditching thermostats if present what other cooling tricks can be used to specifically cool them down and keep them that way? Any old Deflector Alky Merc tricks of any use?

As far as cooling on the 56 cu in blocks, we had many variations to the cooling system on those engines, if you look at the bridge port engines you'll see we changed it at least 6 times between 86' and 93', and after we came out with the 94' oval port engine the cooling system was corrected as well as the piston fit was tightened up.

If you have a bridgeport engine, look at where the water by passes at the bottom and on some of them you can plug that all up and get some more direct flow, some you'll see an angle drilled hole up the bottom headed toward the exhaust side of #2 that was to cure a hot spot next to 2, if you plug that you'll stick it, if you have that block. You'll see other ones with 1/8" pipe plugs to plug some cross drilling we tried, some helped, non corrected the issue til 94'.

When I was at OMC I baby sat this thing through all these changes.

[Fast Fred]

good stuff, can you tell us more on the coolin system of the 56er.:cool:

testin is key,:cool:

i'll check out that Konig stuff.:cool:

i talked to a Dude that worked at OMC, he built Mod50 31m Modas and dynoed them. he said that he used a 56 case, a 31m front 1/2, long rods, trick pistons,
and down exhaust and put it on the dyno and made a pull.

got more, i gots to go now, go and test motors, it's cool kinda fun.:cool:

[Bill Gohr]

good stuff, can you tell us more on the coolin system of the 56er.:cool:

testin is key,:cool:

i'll check out that Konig stuff.:cool:

i talked to a Dude that worked at OMC, he built Mod50 31m Modas and dynoed them. he said that he used a 56 case, a 31m front 1/2, long rods, trick pistons,
and down exhaust and put it on the dyno and made a pull.

Yes we did run 56's with 2 bbls on them, and there were lots of people puttin Merc rods and pistons in them.

I wrote a book on the cooling mods for the in house people back in "93

[Sam La Banco]

Bill, were any of the 56 cuber 2 barrel motors you are talking about able to run strong without the staggered bore 2 barrel set up or extensive mods to the stock exhaust manifold system?

I never saw to many of them, but the ones I saw all had problems dealing with the stock 2 barrels and all the fuel they could deliver. They just did not seem to get up and go, as strong as expected, even with the additional cubes. Not even close to a mod 50. Even with a Mod 50 crank case and reeds.

The 56 cuber manifolds inter-cylinder tunning length in its stock configuration are not suited with or without the SST 60 pipe.

You've seen a lot more of them then I did, just wondering.

[Bill Gohr]

Sam thats always been the issue, the exhaust. I've seen alot of guys do some real nice work on the inside of engines, porting, shaping, even 3 3/8" bores and longer rods, and what are we gonna do with the exhaust, nothing. So most of that stuff never ran worth a damn. You're stuck with the inside casting of the exhaust, and ya need the 60 tuner assy.

When I built the prototype personal watercraft engine, Macier made a exhaust manifold that was 60 dimension but turned 90 degrees, and I made the engine lay on it's face and put super BN's on the side, now that motor would accelerate with those pumpers on it, I had 38's on it to do our boat testing, I was gonna grind on it and go with 42's but marketing pulled the plug on the OMC "Shockwave" personal watercraft. I never had the time to figure out if it was the carbs that acted so well or the fact that when I shortened the front of the engine, all the way to the crank, and put the carbs on the side, was it the smaller crankcase?

And you are right, the best carbs were the staggered bores, I think that little motor just didn't have the signal it needed. Well we know it didn't, thats why those carbs worked.............

[Sam La Banco]

Thanks Bill,

If I can figure out how to do it, I will post some pictures of an intake manifold I designed for the 3 cyl. OMC engines. It was designed to adapt large single barrel pumper carbs of up to 1.770" bore diameter to the stock intake manifold. I did this for all the same reasons you just talked about. I had some casting of it made and machined. When I was going to build an sst70 motor. I thought I would have better luck with large single barrel pumpers than the dual barrel set up.

Then the power head just sat there for years all tricked out with finger ports and the whole ball game. I even machined out the cast in manifold, and made a new one. I finally sold the thing Whittingtons in Canada. I don't think they ever ran it.

Maybe someone would be interested in one of the manifolds if they would want to try the same thing.

[Bill Gohr]

Yep those pumpers were like fuel injection, you just look at it and it was running, I don't think I put a primer on it, you could just start it and grab a handful, nobody in house liked to see Mikuni's on our engine.

[Sam La Banco]

There is a great story about when they could not start the rotary motors and the Mikuni guy was there. But thats a story for an other day.

[Detroit Whitey]

I`m in the middle of doing just What you guys are talking about.I gave the two barrels a try and that was a wash so i`ve been playing with all types of carb & intake set up`s. Had to much of a problem getting it to start on a off the dock start i ended up going back to the sst60 carbs.Well it works but i know like all of you know there`s more so i`m back to the drawing board. Liked the the cooling talk also. GOT A QUESTION why are the guys running the 49ers in the mod classes running the water backward from stock? Sam your adapter looks great but what would you do for the reeds?

[formeone]

just food for thought and i didnt read all the reply's but all you talking about bigger carbs????... i own the kilo in class ..and i used the 55hp carbs????...go fig,,,maybe just set up?? or lots luck????...

[Fast Fred]

anywho, at test done at the factory on the 56er, with, without modded exhaust, long rods, 2bbls, it never made more than 102hp no mater what.

in tests done by my number one tester, at 800ft it's all 56er, low end torque is better.....

? don't know whats to tell yas on the 2BBLS, thare are two kinds, first kind is Mod50 carbs the other kind is all the rest, mod 50 has a specific main nozzel,
with out the nozzel the moda will just wash out with fuel.

my carbs took a lot to work out, the hull Leaves out in like 5ft, on plain and pullin as hard or harder than any Ruba boat i've ever seen:cool:

[Fast Fred]

i gots a Mod50 with press in liners, has the 56er exhaust port, she needs new sleeves, think that would be some thing you could do
Bill Gohr

[Sam La Banco]

Hey Detroit Whitey, I used the stock reed cages, I added one more openning in them, there is enough room on one side. Made a fixture to hold the blocks and machined the holes. Modified the crankcase opennings a bit.

The whole idea was to get a better (modern) carb on the motor, one that could be "tunned" better than the stock carbs, which are very crude compared to newer designs. I knew the motor could not deal with a lot more fuel.

I think the guy's are trying to run the water backward because they found that was how we set it up in the SST 45 motor when we were developing it. It ran better running that way, but that doesn't mean all motors will, don't know about the 49 cuber. As far as I know it doesn't have any cooling problems that I know of. Will it run better with the water running backwards, only testing will tell.

[Bill Gohr]

Hey Detroit Whitey, I used the stock reed cages, I added one more openning in them, there is enough room on one side. Made a fixture to hold the blocks and machined the holes. Modified the crankcase opennings a bit.

The whole idea was to get a better (modern) carb on the motor, one that could be "tunned" better than the stock carbs, which are very crude compared to newer designs. I knew the motor could not deal with a lot more fuel.

I think the guy's are trying to run the water backward because they found that was how we set it up in the SST 45 motor when we were developing it. It ran better running that way, but that doesn't mean all motors will, don't know about the 49 cuber. As far as I know it doesn't have any cooling problems that I know of. Will it run better with the water running backwards, only testing will tell.

Thats the way it was always done on race engines, starting with the KC13.

And I agree with Sam, those motors have plenty of reed area with just some modifacations, we made mod 50 stuff with 4,5, and 6 petal assemblies which never really helped anything, maybe made some peak power over 9K but didn't help anything else.

As far as the carbs go, you need to buy Sam's adaptors and fit some 42mm BN's to it. The one barrel set up came out in what 1968 with minor changes, of course a different carb would be better.

[Fast Fred]

had me some of them Mikuni fed 3cyls 2 strokers. after many tests it is my opinion that the 56er is geometrically challenged, and is not capable of the peak
hp of the 49,i've heard tails of dynoed 56ers hittin 115hp. we can see in ads
for SST60 power heads with dyno slips, a nice one is about 100hp , finger ports
would , could make about 12-15hp.:cool: some slide bores could be nice:cool:

[John (Taylor) Gabrowski]

Being new to the 49 inch OMC 3 Holers having bought a new NOS complete block and all the parts from its blown up predessor fishing engine, looking at carb inlets sure has me puzzled. Like why are these casting obstructions that change direction in the carb base flow are so abrupt? It would seem something could really be improved upon there to make tunning better? Have any improvements been made in this area to improve air/fuel streaming or was it all very good to begin with even with these kinks? Or is this forbidden territory rules wise?

I have set Mercury Twister racing sled reed boxes from a 440 that in effect are in front of the piston port where these sleds used 1 Tillotson HD per cylinder. The reed boxes must have been installed to inprove on midrange power that would have been installed because of piston port spit back problems. Even these reed boxes have a split bar immediately under the carb dividing the air/fuel stream in 2 to saturate both sides of the reed box before going into another HD carb sized inlet port facing the piston port. All this air/fuel stream splitting and changing air/fuel direction must ultimately affect overall power negatively would it not. I am actually thinking of bolting a Mercury reed box like these on to an Anzani and then bolting the Vacturi on top of it because that engine has tremendous spit back at low to mid range high side rpms where the motor finally catches up and does not let the spit back come out of the engine anymore.

What are your thoughts?

[Jeff Akers]

just food for thought and i didnt read all the reply's but all you talking about bigger carbs????... i own the kilo in class ..and i used the 55hp carbs????...go fig,,,maybe just set up?? or lots luck????...


Hey , Cheyney good to see you snoopin around on the net again, you planing a comeback soon ?

The engine that Fred is playing with is using the shifter gear case and on much bigger boats than what you and I drive. and the rules are different allowing more mod's to the intake and carbs. some of the info doe's however cross over to Formula E. Definitely some great info for those wanting to get the most out of an OMC 3 holer ! .... Oh, FYI:...... I use the small bore carbs on my engines too.;)

[formeone]

jeff,,, will be back raceing this comming summer,, liveing in spokane now,,, soo hopefully can get going above 100mph again,,,we shall see,,,

[Fast Fred]

http://i41.tinypic.com/29zd2js.jpg
:cool::eek::cool:

[Fast Fred]

ok, this is the port map:cool:

[Bill Gohr]

I think it was who said it would be nice to have adjustable carbs like a Mikuni, so you could just turn the screws rather than change jets. What about a set of 3 of these trick bad boys????????????

[John (Taylor) Gabrowski]

I have several sets of 3 OMC 3 Holer single barrel carbs used on the 49 inchers and I was wondering out loud if they could be converted to adjustable high speed (screw in or out type) high speed jet needles. With your picture using the two barrel that question has been answered real well! :)

On the Minkuni round slide side of things, they did produce a version for snowmo use that once you had the rest of the carb figured out for base mixture control it had a bottom of fuel bowl adjustment screw to vary the jetting a bit more to deal with temperature variations affecting tunning that worked remarkably well on snowmo sleds on gasoline. I have on of those to put on an Anzani update hybrid given I have enough parts left over to build one in the future to toy with.

[Fast Fred]

seen needles like that on the low speed of a 55hp 3 banger. low speed circuit never stops pullin, so with a needle in the low speed, and the main within range , you should be able to fine tune within the best ability of the carb.:cool:

then, or after that,:eek:
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[Fast Fred]

hey J.T. you out thare? hears them shots of the rig i'm runnin as tested.
that set above, fuel injection, ya 3 banger fueler.:eek::cool:

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[Fast Fred]

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[Detroit Whitey]

Just cant be so Fred with all your know how why are ya still running that old 2ear clamp braket.you`ll find out that they are not made for what our boats can do.Almost bought it at the gold cup this year when one of the ears broke clean in half.

[Fast Fred]

got 4 more for backup, usein grade 8 to hold it on thare:cool: lets see what you got.:eek:

[Detroit Whitey]

You are just gonna have to come to topO this year and find out.I`ll see if i can get some pic`s on here. Kept bustin the ss pins at the top on the old ones and i might have like 5 hole old style brakets left over.I wanted to have a bit more adjustment so i fabed up a hyd assist braket and welded some negative in it then i beefed up the pivot tube. Itell ya its real nice being able to tilt your motor up when your beaching or running thru some real skinny water

[Tim Kurcz]

Thought the group would like to see my long in the planning Mod-50 project. From 50-100 is only 5 seconds..... incredible! I've been humbled, and have no desire to top end it!

Tim

[John (Taylor) Gabrowski]

I never paid attention to what a Mod50 was all about. Now I have some beginning idea. What a motor Tim! Your talking 5 seconds to accellerate from 50 to 100 miles per hour. You must be sitting against a good form fitting seat to do that and then pull a tight turn! :)

[kraazyboat]

Can we see rest of boat?? Dave

[Tim Kurcz]

This is my Ropp FE hydro, normally quite stable at 100......... The beast I built last winter is 8# lighter and much more powerful. In this image, I'm loafing by at 75-80 mph. It's a wonderful ride, only limited by the driver!

Tim

[John (Taylor) Gabrowski]

Tim:

Looks like your just out for a Sunday drive, sitting comfortable floating it all just off the water nicely.

[Tim Kurcz]

While cruising the lake at 60, there are occasional challenges which are quickly dispatched. Here's a shot with the hammer down. Do you like the roostertail?

[Roy Hodges]

[QUOTE=Tim Kurcz;66257]This is my Ropp FE hydro, normally quite stable at 100......... The beast I built last winter is 8# lighter and much more powerful. In this image, I'm loafing by at 75-80 mph. It's a wonderful ride, only limited by the driver!

Tim............................................... .................................................. ...............................
.................................................. .................................................. .................................
What kind of tower housing are you using ?

[Tim Kurcz]

It's a custom tower I built that uses internal exhaust; it's quiet enough to run around the lake with no noise complaints. It accomodates the 45SS gearcase and 49 inch powerhead. The casting is sectioned from a V-6 OMC.

[Roy Hodges]

This would have made the OMC factory engineers proud, & maybe jealous ?

[John (Taylor) Gabrowski]

Tim:

Its nice to be able to create the stuff the way you do, but how do you sleep at night as there must be blinken lights constantly. LOL! Great to have a machine shop at your disposal too boot.

The only thing that had 3 cylinders that ever howled high rpms around here outside of those Merc and Mariner 2 carb 3 banger direct charge hernias that basically gowled was a restored Crescent 500 Super C with its internal megaphone stack and it was interesting but nothing like a dry stacked Quincy or Mod Merc. Now there is a Crescent Toronado 3 cylinder here going the same restoration route sitting on top of a O'Dea tower casting, Merc clamps and Crescent gearcase with the same bolt up to Crescent type internal stack. With the bigger bore, maybe bigger stack and bigger noise? Funny thing when some one ID'd the engine for me some one else said that when its done I should leave it at home! Do you know anything about these as I understand they were tunnel boat engines over in Europe and my exposure to them has been nil?

[Tim Kurcz]

You're right about creating in my sleep and building overnight. Many times my best ideas come just that way. Also do solutions to the most difficult engineering problems. Thanks all for the kudos on the tower and engine. This one took about 80 engineering hours and another 80 to build. Yep, alot of time, but the results speak for themselves.

As you point out access to a machine shop helps. More important in my case was the 15 years spent as apprentice under Bud Parker. A great stash of 2-stroke engineering manuals and a few buddies in the marine business help solve the greatest challenge to all racers: Parts!

Like the old Mercury slogan: The race never stops!

[Sam La Banco]

As one of those factory engineers, especially the one that designed the 45 race conversion parts, it is cool to see what can become of your work.

How many hours on the lower unit? We used the old Harrison 1:1 gears in it because their was not enough budget to start from ground zero.

That 3 cylinder is going to put quite a bit more torque through the unit than the 45 motor or the Harrison stuff ever did, I would keep an eye on it.

[Tim Kurcz]

Hello Sam,

There are about 5 hours on new gears so far and the oil is clean. Having run FE for years, it was the only case to choose. It's been bulletproof under the 45 and my FE triples, parts are readily available, and props in a useable pitch range are plentiful. The power won't hurt it too bad for laking.

With the quiet tower, noise isn't a problem. But, the Sheriff can tell the difference between 55 mph and 100! With it's ferocious acceleration, you chew up alot of lake and can't stay out too long. So, durability isn't an issue. Even if they last only 25 hours, the ride will be worth every penny!!!!

Tim

[Fast Fred]

you got cast in liners or pressed in, in that case your runnin?
nice rig.:cool:

[Tim Kurcz]

Hi Fred,

That would be the real McCoy pressed sleeve two port. Was collecting parts for about 10 years to pull that monster together. It proved well worth the wait! Here's the business end.

Tim

[John (Taylor) Gabrowski]

Tim:

I have a new 3 Holer OMC 49 cubic inch replacement complete block with innards and all that I bought with an entire blown up short shaft fishing engine at a neighborhood garage sale a little over a year ago now. I have been reluctant to tear it down just to put some other aftermarket pistons in it as opposed to keeping the new factory pistons in it now. I keep hearing this OMC 25 hour life span rumor stuff of some kind tossed around that such a new engine will last until what starts happening? Irregular wear, bore goes out, pistons wear out?? I am new to OMC 3 Holers specifically after being tortured by 3 Holer Mercs and Mariners that really jaded me and these 3 Holer 49 inch OMCs are sure no Merc so they all must have some stories and pointers to go with them all their own I know little or nothing about. Want to share????? Everyone???

[Fast Fred]

gots me one of them McCoys, gots the part number for the sleeves?

25hrs????????????? , thares a Stinger 65hp at the shop, thay got it New back in the day, got way more than 25hrs on it.:eek::cool:

[850cc racer]

ive just found x3 of these fred :eek: .. this one has had a BOOM at some stage looking at it

[Tim Kurcz]

Hi John and Co.,

The 25 hour life limit is about right for of my best blister-sleeve FE engines. It should be noted that's the equivalent of 5 seasons racing mostly at wide open throttle. During this time the engine is expected to be flipped at least twice, run on bad gas with worn spark plugs, and occasionally starved for fuel, cooling water, or lugged (the worst possible conditions). Considering these engines were designed for 70 HP at 6000 RPM and are delivering more like 95 HP at 8500 RPM, what do you expect? My developmental engines were lucky to make 10. The 20+ pistons in my "offerings to the God of speed" box tell stories, along with my engineering & testing notes.

The single most important thing to remember is a high ported OMC loop triple requires tandem vacuum pumps or an electric. Fuel starvation is your #1 enemy followed by loss of cooling water. Daring souls will run pumpless. I wouldn't run one without. So,

If your powerhead has new factory pistons, and you race it hard, run it for two seasons, tear it down, and crack check. If you only run occasionally for fun, don't worry, the cast pistons usually just break a skirt off, blow chunks through the thin case with little or no damage to the engine otherwise. A little welding, a new piston, and voila' you're back on the water.

Good luck!

Tim

[850cc racer]

Hi Tim, what fuel pressure have you found works best? using electric pump

[John (Taylor) Gabrowski]

Tim: I take it that 2 OMC fuel pumps looping through the 3 carbs is playing it fail "safer" than any single pump. I have some experience with Holley 12 volt pumps and fuel pump pressure regulators as well as Dupree 12 volt pulse pumps too from playing with turbocharging smaller automotive stuff but nothing on outboards. Stick to a minimum of 2 OMC fuel pumps?? Somewhere I heard that these OMCs also bring in water for racing different than stock fishing use. Is that adding on an extra line opposite each cylinder through the water jacket outer including what comes up the base? I am hearing that OMCs from 35 horsepower and up heat up real fast.

Actually from that 25 hour description that is taking a pounding at high rpm no fishing version would be put through is pretty dang good alright. Being a Merc fanatic (excluding 2 carb 3 holers) early on and for so long gives one false opinions based on the older non-loop OMC engines where I as others would term them being worked on by the hammer, screwdriver and crescent wrench crowd. Seeing what is going on these days on those and your engines by example would get one a poke in the eye or a vicious clubbing about the head for expressing such sentiments anymore for sure! LOL! Now I find myself being the enlightened and converted!:)

[Fast Fred]

you are a long way from a 25hr life span with a stocker or a Mod Stinger,
the one ring Mod50 piston, the long rod makes piston speed faster, the BTUs made, ya a long ways.

it cool to see all three units, the 19s, the Straight-in, and the 31m.

any body gots a set of liners?:cool:

[Fast Fred]

the only notes i could find on Mod50 fuel pressure was 3-5psi, 80gph min.

the 80gals per hour is the minimum.:cool:

[Tim Kurcz]

Let me answer a few Q's:

1) 3-1/2 psi regulated with a bypass is best.
2) The standard pump does not deliver enough to fuel at 8500. I size up my competition by observing fuel systems. If their engine survives on one pump, I know they don't make anywhere near the power I do.
3) OMC makes an excellent suction and pressure pump package. Check the 35HP triple parts catalog for numbners.
4) I'm a factory trained Merc mechanic (from the 70's) and agree the worst engine they ever built was the two-carb triple.
5) OMC cooling systems were designed for thermostats and quick warm up for driveability in fishing engines. Removing the stat and reversing water flow can improve critical cylinder cooling near exhaust ports.
6) Very cool European F-3's with the reversed exhaust. Quiz: 10 points to the person that explains why this was done (I know the answer).
7) Engineered/built properly, this 40 year old design will produce 2 hp / cu in!.

Good luck.

PS Hint on fueling: Brake fuel specific is about .45 lbs/hr/HP. Do the math on fuel flow.

[Danny Pigott]

Tim, how did you get Paul Kalb to tell you about the European f -3 just kidding. Paul had a lot to do with that motor as i remember.He was a friend of mine for along time, i spent a few nights with him at his house before he went to Europe. He gave me a lot of good info. I knew Bud Parker for many years also, you had a good mentor, saw him last at Cresent City Fla. in 2000.Bud once told me you work on the motor to get the last H.P.work on the boat to get the last mph an when you get to the race it's too rough to hold it wide open anyway. The EX. is reversed on the E.F-3 because Paul wanted it that way an Jack Leek wanted it another way, they did not see eye to eye.Do i get the 10 points lol. I think this was done so they could counter rotate the engine in Europe due to gravity difference from the U.S.

[Tim Kurcz]

Hi Danny,

If you had said exhaust anti-rotation for use down under, I might have given you the prize LOL, but no cigar........ Please try again!

It's nice to hear you knew Bud. What he told you was true: I didn't have the driving skills to beat the VanOvers, Withams, Robbs and other "big shoes" of the day. The only way to beat them was on raw power. Bud and I improved the "underdog" 45SS with its "huge" gearcase. Combined with a 12' Ropp hydro (The Pink), the rig proved almost unbeatable in 1991. The tricks he taught me were/are indispensable. I do my best to transfer the knowledge to any/all who listen. Just like you, the sport is in my blood.

Tim

[Ron Hill]

You'd want the exhaust pointing up, down under, right???

[Danny Pigott]

Many years ago i was told that the OMC 3 cylinder design was started at Mercury,the engineer that designed it was fired an went to work for OMC an carryed his design with him. It became the OMC 3 cylinder.Anybody know about this, was it true or not.

[Mark75H]

Many years ago i was told that the OMC 3 cylinder design was started at Mercury,the engineer that designed it was fired an went to work for OMC an carryed his design with him. It became the OMC 3 cylinder.Anybody know about this, was it true or not.

That is probably a reference to Charlie Strang

[E-tec1]

lets just say its for the same reason that certain mod 50s were run reverse rotation, if i remember corectly

[Ron Hill]

I recently appropriated several OMC propellers, and they appear to be MERCURY PROPELLERS with OMC bushings....I'd guess OMC went to left hand because these Mercury wheels were very good and they could buy, one or two at a time or as needed....

I know Bobby Herring was a big one to like the left hand rotation as he believed the boats turned better with left hand rotation...

What years are we talking here???

As I do know that when Fred Hauenstein went to work for Mercury, Gary Garbrecht purchased every piece of my Evinrude equipment at a MORE THAN FAIR PRICE (My stuff was triple CCC V-6)... Fred started at Mercury in the fall of 1978 or spring of 1979! I as told at the time, so Mercury would not have a problem with Fred hauenstein working for them...That any secrets he might have had, they purchased from MY motors...which just happened to come from Freddy Hauenstein!

Rumors that I heard, was that Fred had designed OMC's 2.0 liter before he left OMC, but never heard anything about the three cylinders race motors.

I sold OMC, Europe, MOD 50 props, 10 at a time and they were reworked Mercs, but right hand 10 X 15...or so...

Note OMC prop bushing in Merc prop.

[Danny Pigott]

That is probably a reference to Charlie Strang

You are right Sam, Charlie Strang was who i was talking about.

[John (Taylor) Gabrowski]

If that story was true then he left behind his revenge in the form of the 2 carb 3 Holer semi-deflector Mercs and Mariners that caused so much heartburn!

[Tim Kurcz]

Do you mean exhaust like this for down under?

Still no takers on the reverse exhaust? BTW; the engine turns clockwise as viewed from the top, same as all the other.

About RH -vs- LH props. A trick question for the group: Does a RH prop help or hurt progress around a LH race course?

Answer to the fuel question: .45 lb/hr/hp X 95 hp = 42.75 lb/hr / 6.0 lb/gal = 7.125 gal/hr X 1.25 for rich cooling effect = 8.9 gal/hr. So how much pump delivery do you need?

Tim

PS Note the tandem pumps.......

[850cc racer]

Hey Tim you have some neat looking stuff.. are the rubber hose snorkels to stop water getting in? or? only reason i ask.. im not 100% sure but is there something about the intake length has to match exhaust or portion there of?:confused:

[John (Taylor) Gabrowski]

Tim:

Thanks for this information and pictures. Dual pumps well put. I have an abundance of the older pumps too, are the pressure and flow on those older ones which I use to fuel Anzani engines and now some Mercs too comparable to the mounted OMC pumps in your picture?

The exhaust zoomy off the top and the dump out the bottom of the 2 different engines much different in performance?

I get a kick out of the skegless gearcase and then the large fin off the left afterplane of the raceboat. I have bottom skegless gearcases but my present understanding of them purely was for kilo and mile speed runs trials. Is that the same for the pictures or is that the way the raceboat runs as a Super E oval track boat with the skegless engine?

Neat stuff! :)

[John (Taylor) Gabrowski]

The engine being reed valve induction and all do the add-on plastic bent carb opening stacks to avoid water ingestion any liability to the carbs and engine due to the bend involved tampering with the direction and other dynamics of the airflow?

[Detroit Whitey]

I went to the 2 pump set up a few years back but had issues with fuel eating the diaphrams.i ended up going electric and after that no more melted pistons wich is nice.

[John (Taylor) Gabrowski]

How long are the diaphrams lasting with the present gasoline your using? What kind of gasoline in terms of brands, octanes etc? Would running aviation gasoline resolve the problem?

[Fast Fred]

reg rotation, the cyl gets a better seal on the power stroke, the Moda makes 10-12 more hp than the port side exhaust case.:cool:

[Tim Kurcz]

Fast Fred takes the points. Torque side piston rock with the port side exhaust allows exhaust gas to blow by the ring. Exhausting on the starboard side eliminates that problem........ Bravo!

[Ron Hill]

Does this rotation "THING" have anything to do with Merc's racing V-6 running in reverse (left hand)? Or does this only apply to these three cylinder OMC. Please should some pictures.. I think I understand what you wrote, but it doesn't compute in my head...

[Danny Pigott]

lets just say its for the same reason that certain mod 50s were run reverse rotation, if i remember corectly

So you are saying that some Mod 50's were run reverse rotation. Jimbo told me once, that there are Mod 50's an then there are Mod 50's.This way he gave away no secrets. I asked him why my Mod 50 would only run 85 to 90 mph. he said that is what most Mod 50's will run.He did not mean his.

[MN1]

I think it has something to do with the exhaust tuning. (The pipe at the top and or the left hand rotation).
Mark N

[Tim Kurcz]

Sorry to keep you all in suspense today, and many thanks to Ron for his head scratching response regarding my teaser of an exhaust positioning explanation. All of you forwarded various pieces of the puzzle; I was waiting for one of you take me to task for leaving one out a BIG one. I'll try to "plug the hole" now with a better explanation.

You all know the piston needs clearance in a cylinder bore to move. In engines which rotate clockwise (viewed from the top down), the piston is forced to the starboard side of the cylinder by the connecting rod during the power stroke. Sure enough, there will be leakage of exhaust gas past the ring and piston on the port side which will cause some contamination of intake gasses below the ring for the next stroke. But,

There's a much more critical event which happens beforehand. Consider the piston is tight against the starboard cylinder wall. This means the clearance is on the port side. So what happens as the piston begins its downward stroke before the exhaust port opens? Crankcase gasses under increasing compression travel past the piston skirt and right out the exhaust port!

So, by reversing port locations in a right rotation engine (as viewed from the top), you effectively use the piston to "plug the hole" that gasses would otherwise escape through. The result is more power! The opposite is true for those down under..... if you're spinning left hand rotation engines - LOL!

Unfortunately for FE builders, we have no choice. Or, do we? How many of you have "low ported" a cylinder thinking you'd get better exhaust scavenging? Or run larger piston to wall clearances to loosen up the engine? In either case you've actually improved the ability for crankcase gasses to escape.

Does this make more sense now?

Tim

[Fast Fred]

with starboard exhaust the piston rides the exhaust side of the bore on the power stroke for the better seal, it's also the hot side, works it harder. works the same on a V6.

most likely had a newer Mod50 powerhead, each one made about 10 more HP than the model before it.;)

:cool:

[Tim Kurcz]

Only one comment Fred: Because the exhaust runs down the middle, it works for only 1/2 of the V-6.

[Danny Pigott]

Sorry to keep you all in suspense today, and many thanks to Ron for his head scratching response regarding my teaser of an exhaust positioning explanation. All of you forwarded various pieces of the puzzle; I was waiting for one of you take me to task for leaving one out a BIG one. I'll try to "plug the hole" now with a better explanation.

You all know the piston needs clearance in a cylinder bore to move. In engines which rotate clockwise (viewed from the top down), the piston is forced to the starboard side of the cylinder by the connecting rod during the power stroke. Sure enough, there will be leakage of exhaust gas past the ring and piston on the port side which will cause some contamination of intake gasses below the ring for the next stroke. But,

There's a much more critical event which happens beforehand. Consider the piston is tight against the starboard cylinder wall. This means the clearance is on the port side. So what happens as the piston begins its downward stroke before the exhaust port opens? Crankcase gasses under increasing compression travel past the piston skirt and right out the exhaust port!

So, by reversing port locations in a right rotation engine (as viewed from the top), you effectively use the piston to "plug the hole" that gasses would otherwise escape through. The result is more power! The opposite is true for those down under..... if you're spinning left hand rotation engines - LOL!

Unfortunately for FE builders, we have no choice. Or, do we? How many of you have "low ported" a cylinder thinking you'd get better exhaust scavenging? Or run larger piston to wall clearances to loosen up the engine? In either case you've actually improved the ability for crankcase gasses to escape.

Does this make more sense now?

Tim

Tim I can see what you mean.But why was the engine not built this way in the first place. An why are all inline motors built with the ex. on the right side.The Mark 58 merc. had in line wrist pins, they cause piston rattle. so merc off set them to stop this.I think the in line pistons were better because of what you said about the f-3 ex. piston seal.Would not reverse rotation do the same thing move the clearance to the other side of the cyl.

[Fast Fred]

ya, only works on one bank of a V6.

the intake is the cool side of the bore, it's easier on the parts to run the cool side.

thinkin with a 1 to 1 lower unit with two or more pinion gears, spinnin backward
may or may not be better. don't think it's guna work out with the Nitro foot.:cool:

[seaward]

Tim
Do you run a single pulse line to both pumps or do you use 2 different cylinders for pulse pressure.
Hal

[Tim Kurcz]

Run one each from the #2 & #3 cylinders. Be sure to use high strength Loctite in the fitting in #2 as the casting is pretty thin.

Tim

[John (Taylor) Gabrowski]

Tim: I keep hearing stories that the OMCs of this era have very thin castings of what some term poor aluminum that its so porous it leaks? The 3 Holer here does not look or feel light weight so what is behind the stories and what can one do to make things better if so?

[Tim Kurcz]

Hi John,

I've never heard or seen such a thing, and have built dozens myself not including the untold numbers I worked on as a marine mechanic in the 70's. In it's original form (55 Triumph) it outstripped the very popular Merc500 and dominated the racing world. Is it possible Mercury lovers were just taking pot shots?

Tim

[John (Taylor) Gabrowski]

Tim: I have been and still am a Merc freak of the craziest variety. Coming from you with your Merc and OMC background well, that is confidence in OMC castings for people like me just getting in to them. Yes some people did put some notions in my ears but that is changing obviously. Its quite real that the OMC 45 2 cylinder racing engine is one way stronger motor than any Merc or Mariner 44 cube stock racer, that is why they put the 45SS into Formula E and 45SS tunnel boat racing right off. This OMC loop technology was superior to Mercs old style deflector/crossflow techologies that really didn't change much other than peripherals since the early 1950s.

[ram95]

Tim I can see what you mean.But why was the engine not built this way in the first place. An why are all inline motors built with the ex. on the right side.The Mark 58 merc. had in line wrist pins, they cause piston rattle. so merc off set them to stop this.

Danny, the offset piston pin came into play because of the direct-reversing inline six (mk 75 and mk 78 engines ) aka 'dockbusters'.:o. These engines had no neutral and had a bi-directional starter:confused:. So to back up you cranked it up in reverse. With the center pins on the deflector pistons, the engine would rattle:eek: - customers were concerned. Carl was concerned.:mad: So they offset the pin to quiet things. The 58 & 78 used the same pistons.

alex

[ram95]

How long are the diaphrams lasting with the present gasoline your using? What kind of gasoline in terms of brands, octanes etc? Would running aviation gasoline resolve the problem?

John, the problem with "gasolines" now in most parts of the country is the introduction of ethanol.:eek: Without getting into all the technical crap too deeply, suffice it to say, it's un-stable $hit.:mad: Avgas on the other hand IS stable. The MilSpec says it's got to stay perfectly good in a 55 gal barrel for more than 10 years!:cool: Avgas, of the type you can find at most any little airport is of the 100 octane variety. It's referred to as 100LL, the LL being for low lead. It burns nicely, but you will see some deposit on your pistons or plugs tho not much. I always run it. However, I don't mix oil with it until I'm at the race site. Why? because I really don't know how it likes being mixed with TCW3.

Alex

[Mark75H]

The storage spec for AV gas is 2 years

I don't see any deposits on my plugs or pistons ... it stays mixed well with any oil. I often use gas mixed the previous summer in the spring the next year

[850cc racer]

hey guys quick question: i have a 56 cuber part number is 340899 i cant seem to find it on parts catalogs.. what would/should be the standard bore? it measure approx. 3.178 and it has one big oval exhaust port:confused:

the other one i have 334474 measures 3.220 and has 2 exhaust ports :confused:

any help appreciated :cool:

850

[Fast Fred]

the oval port is newer, the oval exhaust port make of a more rounded power band. the split exhaust is the one, cuzz of the bridge it can be made bigger over all, you can incorporate the oval style in to the split port.:cool:

standard bore is 3.187, 3.220 is a bit big for +.020 but small for +.030's

[Detroit Whitey]

Also find a block without the idle bypass hole in front of the exhaust

[850cc racer]

okay, only that im going to use the block with the oval exhasut port, as the other block needs sleeving and 3 pistons, so i should be able to use 20 overs in the block that measures 3.178 app.

also i was going to try Vertex pistons.. anyone used these before? :eek:

thanks for the replys.. the block with the 2 piece exhaust port will be the one i build as a spare in the off season.. might even get some methanol burning in this one!! :eek:

[850cc racer]

was just re-reading what fred posted and yeh it had +0.30 in it.. thats an approx measurement but wouldnt be that far out..

what clearance do you run thare Fred?:eek::cool:

DW: ahh yes this one does have the idle relief hole too but much smaller then the motor i took off the boat, is this a real negative thing to have?