School me on OMC V8 Outboards

[NoLimits]

I'd like to learn more about the 2 stroke v8 OBs that OMC made, but strangely, there does not seem to be a website that covers them well. I would think there'd be a history, specs of different models, etc etc etc. I want to know more about them, are there any good resources? I've been googling and there are a lot of random threads on S&F but no real decent thick ones.

[WaterZebra]

I'd like to learn more about the 2 stroke v8 OBs that OMC made, but strangely, there does not seem to be a website that covers them well. I would think there'd be a history, specs of different models, etc etc etc. I want to know more about them, are there any good resources? I've been googling and there are a lot of random threads on S&F but no real decent thick ones.

Lars Strom would be your S&F OMC V8 expert. He's a retired Evinrude dealer and raced OMC V8s. He has a thread under Outboard and Racing history dedicated to OMC stuff.

[NoLimits]

So there is not a website or general FAQ about them anywhere?

[WaterZebra]

So there is not a website or general FAQ about them anywhere?

If you searched the internet and came up with nothing, you have your answer. OMC,dealers and parts suppliers are long gone. Racing V8s are owned by collectors and production versions are seldom seen on water. Bombardier Canada scrapped what was left of the OMC V8 program. The V8 package reached its peak in the late 80s. OMC had to "stock" dealer inventories themselves as they were not selling and dealers wouldn't finance engines that buyers didn't want.

[FUJIMO]

...yup...what zebra said...

[billybob]

Forget the V-8 Go with a modified OMC V-6. You can modify one & make 250+hp. at over 7,000 Rpm minimal.

[LakeFever]

The V8 omc is a motor of legendary status make no mistake about that. It holds two titles that appear to be unbeatable at this point. One is the outboard speed record set in the mid 80’s. Here’s the documentary about it

https://m.youtube.com/watch?v=bLDM1kE8pVw&pp=ygUXV29ybGRzIGZhc3Rlc3Qgb3V0Ym9hcmTSBwkJxwkBhyohjO8%3D


the second title the big OMC V8 holds is the best sounding outboard ever made. A full song v8 rude is an incredible experience. During the manufacturing period in the 80’s a division or corporate sideways outfit whatever structure was born called second effort racing. These guys made racing lower units and other racing parts for the v8 motors. Most of this stuff was run in salt water and if you find any of it most of it is junky used up stuff.

That’s the romantic side of it. The reality of them today is good ones are hard to come by and parts to repair them are even scarcer. If your serious about getting one of these together for a true hi performance application Monty is who you want to speak to at Monty racing dot com.

id love to see a fresh top tier v8 omc rig. Go for it

[powerabout]

I'd like to learn more about the 2 stroke v8 OBs that OMC made, but strangely, there does not seem to be a website that covers them well. I would think there'd be a history, specs of different models, etc etc etc. I want to know more about them, are there any good resources? I've been googling and there are a lot of random threads on S&F but no real decent thick ones.

Ask away on here, many people have lots of experience including OMC factory engineers on both the production 3.6 4.0 and the custom race engines 3.5 then 3.0 carby and injected.

[Instigator]

There were two basic designs, and totally different.

The recreational version came in 3.6 and 4 liter version in power from 250 - 300 hp.

These hand standard shiftable gear cases.

Many people think the race version started there but did not.

They were 3 - 3.5 liters and 390 - 400+ HPs.

These had direct drive race gear cases on them.

[powerabout]

Race motors came before the production engines

[powerabout]

There were two basic designs, and totally different.

The recreational version came in 3.6 and 4 liter version in power from 250 - 300 hp.

These hand standard shiftable gear cases.

Many people think the race version started there but did not.

They were 3 - 3.5 liters and 390 - 400+ HPs.

These had direct drive race gear cases on them.
Hi Instigator
Can you post the link to you rlong thread on V8's
Lots of info there

[Instigator]

i’ll have to see if I can find it.

Last time I used the search feature I finally got pissed off and gave up!

Never has worked very well.


Hi Instigator
Can you post the link to you rlong thread on V8's
Lots of info there

[Instigator]

Hah, hah, hah!

I just searched:

V-8, by Instigator, any thread and here is the result.

[FUJIMO]

https://www.screamandfly.com/attachment.php?attachmentid=544428&d=1754740703

[FUJIMO]

...on a side note gator...i had no idea you could put a v-6 johnrude block in a gas BBQ grill to heat it up to pull the sleeves & push in new ones! the things you can learn by going to OMC tech school are amazing. lol (just mess'n with ya gator);)

[Instigator]

I learned that right here on S&F!

An oven works better but it will stink up the house for days!

Ask me how I know.

Its actually one of the strong attractions for me, to the OMCs for hot rodding.

Some of us don’t have the budget to support a high end nic 2.5 motor so this works.

I can pop an OMC, assuming no holes, and replace a sleeve, piston/rings and a rod (free from my parts supply) for $300. ($200 if I reuse gaskets which I do a lot) and be back on the water the same day if I thrash.

And have brats on the already hot grill!

PS, I will argue the benefits of chrome/nic w/anyone that wants ��

[NoLimits]

So from what I understand, the pistons/rings/rods/sleeves/reeds/carbs on the v8 are all shared with the v4/v6, and the real hard to find part is the crank. I'm slowly tearing mine down, not sure if the crank is good or not yet.

I'm aware of Monty, but it's getting kind of tiring wanting to learn about these things, and having everyone say just send it to Monty. I want to learn.

So the race version isn't based on the production version? Was it just thicker sleeves/smaller pistons to reduce rotating mass so you could spool it up faster?

What kind of hot rodding tricks can be done to them? Has anyone attempted EFI with Megasquirt or the like?

[racer]

1985 V8 had different reeds, intake manifold, carbs. Sleeves are different (porting) Early V4 had different reeds between the 120 and 140. 1988 all went to a larger bore and slightly shorter sleeve with the V6 going to oval instead of bridged exhaust port. 1993 the V6 got finger ports with a smaller exhaust port. 4 different intake manifolds depending on year. Race version is a totally different block with a shorter stroke crank with smaller rod journals, intake, piston design, removable exhaust chest and more. Yes several of us have installed efi but unless you get one preprogramed you may burn one down a few times before getting it mapped right, having a dyno helps a lot.

[LakeFever]

1985 V8 had different reeds, intake manifold, carbs. Sleeves are different (porting) Early V4 had different reeds between the 120 and 140. 1988 all went to a larger bore and slightly shorter sleeve with the V6 going to oval instead of bridged exhaust port. 1993 the V6 got finger ports with a smaller exhaust port. 4 different intake manifolds depending on year. Race version is a totally different block with a shorter stroke crank with smaller rod journals, intake, piston design, removable exhaust chest and more. Yes several of us have installed efi but unless you get one preprogramed you may burn one down a few times before getting it mapped right, having a dyno helps a lot.

wow. Your library of omc knowledge is unreal

[Instigator]

Thank you Al.

A guy comes on here expecting to get cam shaft part numbers and read 3 paragraphs on how to build a motor that barely exists??

Good luck dude.

You came to the best place on the planet for help and that ain’t how it’s done.



1985 V8 had different reeds, intake manifold, carbs. Sleeves are different (porting) Early V4 had different reeds between the 120 and 140. 1988 all went to a larger bore and slightly shorter sleeve with the V6 going to oval instead of bridged exhaust port. 1993 the V6 got finger ports with a smaller exhaust port. 4 different intake manifolds depending on year. Race version is a totally different block with a shorter stroke crank with smaller rod journals, intake, piston design, removable exhaust chest and more. Yes several of us have installed efi but unless you get one preprogramed you may burn one down a few times before getting it mapped right, having a dyno helps a lot.

[NoLimits]

Dude WTF is your problem? When did I say that?

I'm wanting to learn as much as possible and I'm not finding ANYTHING with google searches other than 'talk to Monty and have him do everything for you'

[Greg G]

So there is not a website or general FAQ about them anywhere?

No nothing like that was ever put together.

[Greg G]

And many of the folks with the knowledge required to do so have passed away.

[LakeFever]

FWIW I didn’t suggest you simply throw money at Monty and call it a day. I did say he’s the best one who knows the right info for working with V8 omc motors in particular. He builds all kinds of wicked omc stuff but the V8 is niche and he’s the man. Surely worth a phone call to pick his brain and at least get set out on the right path. This is a no brainer to me. As with above most of the guys who worked on these motors are quite old now or sadly no longer here as mentioned. Not all that much omc Activity here the past few years

[Instigator]

Here’s your challenge:

1. EVERYTHING you are looking for is on this website!
But, the search function sucks!

So I don’t even know how to find my own, old posts??

2. Writing a check to Monty, which I understand is not your intent, still ain’t all of it.

A high strung two stroke OB is very high strung requires tons of maint/$$$.

Think, 5’8” blue eyes, blond hair, big……, well, you get it.

Merc, OMC both.
It don’t matter.

W/a Merc, if you have problems, there’s tons of people to help you.

A V-8 JohnRude?
Theres only a few of us w/much experience/help and although very similar, 99% of mine is on the V-6’s excep this one I just started.

3. And my smart ass response about the camshaft part # was a hint at the difference between what you are wanting to do Vs, building an LS series motor.

There are 1000’s of recipes, complete w/part #’s ……, that tell you how to build a 1000 HP pump gas motor.

4. Calling Monty and asking for (free) help.
I have done it.

But understand you are taking time out of his day to coach you on a project that he will likely never make a dime off of.

5. W/a hot rod 2 stroke, it’s all about porting.
That you can’t learn from a book.

It takes hrs, hrs, and hrs of experience to know how to do it, where to do it, how big to go, port heights, port angles, plus $100’s of dollars of carbide burrs, a good die grinder and a healthy compressor to power it.

And one slip w/grinder can destroy hrs and hrs of work and a good block.
Ask me how I know.

6. You’re for scavenging 40+ yr old parts from who knows where, zero over counter stuff available, etc and many of the sellers know zero about what they’re selling.

7. I’m 66 yrs old and have been doing this for 30 yrs.
I have helped dozens and dozens of people and 99% of them, listen to 50% what I tell them, make x that in w/their auto mechanic friends and their motor pops before it’s broke in and they have no clue why.

Normally they do it one or more times before giving up, buying a hot rod Merc ( that was hot rod from the factory), tons of parts, tons of help and climbing on the OMC sucks band wagon.

One guy I helped, bragged about how fast h could change a piston instead of figuring out why it kept happening.

Oh yeah, then switched to Merc while bashing OMCs.

So you asked, what the fk?

Howd I do?

PS, it took me 20 mins to type that!

PS,PS, the motor in the pic is a combination of at least 4 motors.

[FUJIMO]

...i see a couple merc parts on that thing gator. so should haul ass...(lol)...;)...https://www.screamandfly.com/attachment.php?attachmentid=544628&d=1755461310

[Instigator]

Nope.
All OMC!

For now anyhow.


...i see a couple merc parts on that thing gator. so should haul ass...(lol)...;)...https://www.screamandfly.com/attachment.php?attachmentid=544628&d=1755461310

[CUDA]

I've known Monty 30 some years, He's as solid as a ROCK

https://www.facebook.com/p/Monty-Racing-Inc-100063652539739/

I recently took him a 90 HP Yamaha to build, I didn't ask for a price and told him no hurry, it's next years project, new finger ported pistons etc.

If you saw one of his V 8 race motors blocks you would be amazed how much work he puts into making one

The area where the intake ports are, is cut open, I never asked how the cutting is preformed but it's a large area outside each intake port area

So after what ever porting is accomplished he has to weld it back together, it's around 3x3 inches square

Monty has had his own line of Pistons made, I believe by Wiseco .

Gordon raced a V 8 Unlimited Mirage back in the 90's when I first meet him through Patrick Eves who was the factory OMC service rep for Florida, Eves was my Factory rep who helped me out with parts, like a free powerhead, he warrantied a race motor once:cheers: NY factory service rep before moving to Florida as i did, mid 80's

Patrick Eves drag raced himself and drew me back into racing after a terrible accident in 85

People tell you to call Gordon because he's the GOAT, and willing to talk...

Just being interested in OMC's he'll be happy to answer your questions with REAL GOOD answers

He's the ONLY person that has made a living modifying OMC's from 3 cylinder SST60's to V8s

The amount of time Monty spends to make a race V 8 is no where near the price he charges, I believe it's $8,500.00

It would be prohibitive to charge per hour because the price would be soo high.

Monty is still drag racing a V6 OMC, and winning:cheers:

https://youtu.be/GpS7U3UyyRo



Those F1 motors that they used in the early 80's ran higher RPMs

You had a big motor on a light race boat, you didn't need

Gobs of Torque

I'm not sure of his final cubic inches but it's high,

and they stay together ! in the old days they were not known for reliability in race form

Monty worked that out, with pistons and porting design

So Gordon goes the opposite from the 80's F1 motors

Torque Monsters

https://images.app.goo.gl/Z6aYaPAjQfnwQ52C7

[Instigator]

When we lived over by him I’d go have lunch with him and Chaz once a month and then go snoop through a through his shop.

I always joked that he patted me down for cameras before letting him in though :-)

I think he may be closer to 40 K for a full race V8 though.

When we first moved down there that time he was so slow that he worked part time at the airport to help keep the doors open.

And then he helped some guys start winning with his loopers and his business exploded, and he may be set for the rest of his life from what I see!

[Chaz]

I miss those lunch's .... :thumbsup:

Sum Merk parts ..

http://i.imgur.com/ZMvDPwql.jpg (https://imgur.com/ZMvDPwq)

http://i.imgur.com/yohwY9nl.jpg (https://imgur.com/yohwY9n)

The guy who made these tiller/ pin/ yoke's had to be sick in the head ... :D :leaving:

http://i.imgur.com/ccXK7NJl.jpg (https://imgur.com/ccXK7NJ)

[Chaz]

I think this one (V-6) went on Gordons Orange Action or his QuarterShot ... :confused:

http://i.imgur.com/EtyNGAxl.jpg (https://imgur.com/EtyNGAx)

[Chaz]

This was a 15" mid for a guy in Miami. He made the billet yellow mounts and black lower unit adapter.

http://i.imgur.com/DZGWcpLl.jpg (https://imgur.com/DZGWcpL)

http://i.imgur.com/HYFTUiSl.jpg (https://imgur.com/HYFTUiS)

http://i.imgur.com/1Xz6A6Bl.jpg (https://imgur.com/1Xz6A6B)

The V-8's had a real small water pick up tube. I made this adapter for a 1" tube. It used an O-ring to seal it. The mock up piece was molly but the final piece was 316 stainless.

http://i.imgur.com/SLuVBxxl.jpg (https://imgur.com/SLuVBxx)

http://i.imgur.com/P229vCml.jpg (https://imgur.com/P229vCm)

http://i.imgur.com/KMyXH5Al.jpg (https://imgur.com/KMyXH5A)

[racer]

Most have no idea how much time is involved to port one of these engines. Sure you can do a quick clean up but a real port job takes a lot of time and effort. Building a 350 hp V8 is not bad but as power goes up the effort and time involved multiplies.

[CUDA]

When we lived over by him I’d go have lunch with him and Chaz once a month and then go snoop through a through his shop.

I always joked that he patted me down for cameras before letting him in though :-)

I think he may be closer to 40 K for a full race V8 though.

When we first moved down there that time he was so slow that he worked part time at the airport to help keep the doors open.

And then he helped some guys start winning with his loopers and his business exploded, and he may be set for the rest of his life from what I see!

When I said $8,500. that is just porting a bare block, nothing else

a la carte, one step of many.

[James45157]

when i said $8,500. That is just porting a bare block, nothing else

a la carte, one step of many.
is that a mercury gear case

[CUDA]

No that's just cutting block open to grind aluminum and steel sleeve to make the intake ports larger, then welding it back together. back into block, I've never saw anyone do what he does, cutting the block open to get inside to do modifications. side area behind the ports wide open,

I really know very little of what he does in there, call him if you want to know. He has not built me anything in 20 some years, I run Mercury's

He is porting the block and new pistons of a 90 hp Yamaha 2 stroke for me over the winter, when he has nothing else to do ;)

He stays busy during race season with big OMC's , He races a V-6 from the 90's and wins a lot.

There is a Gentleman on this board who took him a 130 V-4 Yamaha, He claims almost 200hp from that motor now

That little V 4 on a 13 Biel boat broke 101 MPH, with a BIG fellow driving.

https://youtu.be/vs13AmvP4hQ

[FUJIMO]

https://i.imgur.com/h0wOg60l.jpg

[Chaz]

Worlds shortest, lightest mid-section .. ;)

http://i.imgur.com/tdkYsozl.jpg (https://imgur.com/tdkYsoz)

http://i.imgur.com/ocRFdpFl.jpg (https://imgur.com/ocRFdpF)

[WaterZebra]

Worlds shortest, lightest mid-section .. ;)

http://i.imgur.com/tdkYsozl.jpg (https://imgur.com/tdkYsoz)

http://i.imgur.com/ocRFdpFl.jpg (https://imgur.com/ocRFdpF)

LOL. Mercury started using tube construction on their Verado and V8 mids. Promo guy said it was their version of Ducati engineering.

[NoLimits]

I tried to push tube framed mids when I was working at Merc, no dice. The Verado/AMS mids are mostly castings, with a couple tubes welded on.

Anyway, dudes, this thread is AWESOME. I'm still researching every night and learning more and more. Let's keep this going.

First, I will call Monty at some point but I don't even know enough to ask the right questions. My current plan is to build my 3.6GT. Could I go Merc? Sure. But my boat was originally rigged with this engine, and now that I have one I'd love to hear it bark again. Also, a 22' deep V is kinda big for a 2.4/2.5 isn't it? I would think the torque of the v8s would be more appropriate on this style hull, and a smaller/rev happy merc would be happier on a shallow v/lake boat.

I'm still stripping my engine, but I've been reading about porting a lot on dirtbike and snowmobile forums, not so much information on outboard porting that I've found so far, and it's generally just beveling/rounding the edges of the ports on the sleeve. If anyone has links I am a sponge and spend at least an hour every night reading.

Right now I'm planning on getting the pistons out, then getting the sleeves bored as little as possible to clean them up, round the edges of the ports. Anything else I should be doing while I'm in there? Not looking to build an all out race motor, but while I'm in there I'd like to be aware of other mods.

My crank has some rust on the circular sealing disc things, but all the journals/bearing surfaces are perfect. Current thought is to build an electrolysis bath to remove the rust, as it's not destructive.

One other question re: gearcases. I have a 25" mid with normal looking gearcase. It looks like the 20" mids had an offshore exhaust snoot, and high speed gearcases. Is there a reason this wasn't offered on the 25" mids? And can a high speed gearcase be adapted to a 25" mid by swapping out the taller driveshaft? I've also seen some people running merc gearcases???

Keep it up dudes. And yeah gimmie those camshaft part numbers lmao

[FUJIMO]

...wonder where all the 3.5 litre offshore v-8's are?...

[powerabout]

2 of the gearboxes in Oz

[Instigator]

In kind of a catch 22 situation with finishing the shop.

A. Building funds are on vapors.

B. Can’t set up the shop until interior walls are skinned.

C. Can’t skin the walls until they’re insulated.

D. Can’t insulate until wiring is done.

E. Etcetera!

Good is, Fall is coming and is cooling off so I’m able to work in the barn until mid day before temps run me out.

W/no insulation/walls the barn is giant heat sink.

I put my temp gun on the roof when under direct sunlight and it was 118*!

So I had an epiphany!

So I can start to use the the shop and clear up some floor space, I built a workbench on wheels.
( can’t do much w/o my workbench!)

Not sure how many drywall screws I used but it was a ****ttt ton!

[racer]

If you port it like a dirt bike or snow mobile you will have an engine that does not work well on a boat. The power to weight and drag numbers do not favor the boat. Also rounding ports in the wrong area will kill power, port angles need to direct the flow to the proper area to make power and torque. When each port opens with regard to it's neighbor can also effect power band. An engine ported to push a light boat is not going to work well on a heavier boat. It also becomes a lot more difficult to get jetted correctly. IMO the best thing you could do is just a mild clean up

[mrpenguin]

How difficult was it to convert a V8 OMC to the newer Fastrac clamp bracket?

[powerabout]

How difficult was it to convert a V8 OMC to the newer Fastrac clamp bracket?

Be aware that

The v8 trim is lots stronger than a stock old style
I guess testing found that out...