OMC 3.8 V6 1983 Century Boat. Can I use car long block?

[75GlastronMN]

I have a 1983 3.8 litre OMC engine that has a cracked block.
Is their any reason I couldn't pull a car long block and use the OMC intake and exhaust?
Is anything different?
Does anyone know what year car engines and out of what that will work? Is this a FORD 3.8 litre?

 

[Darkhorse1201]

Re: OMC 3.8 V6 1983 Century Boat. Can I use car long block?

1st - yes you can use a car block. You will need to change the core plugs as autos use steel and boats use brass. Also will have to change the manifolds as you indicated as well as the water pump (boats use stainless insides and better seals) and you may have to change the oil pan. It would need to be close to the same year in manufacture for everything to fit. As far as whether this is a Ford motor - I don;t think so. I belive it wolud be an early GM like what came in Buicks, Olds and such - possibly some early Chevys. I am not 100% sure on this so perhaps some of the more experienced guys on here will enlighten you as to the motors origin. It should be stamped somewhere on the block "GM" if it is one but I can't be sure of that. I swapped my cracked block V6 for a V6 out of a Chevy and it has performed awsumly! But it should work as described and not to hard :devilther than performing the swapover operation as detailed above as well as any thing I may have missed. Good luck!!!

 

[stevieray]

Re: OMC 3.8 V6 1983 Century Boat. Can I use car long block?

Glas - I would suggest that you research some previous threads - engine swap-out is a very popular topic. I have read many & most of the guys here say to use a truck engine since the camshaft is closer to the marine spec in those. You may have some head issues as well as far as bolting up marine manifolds.

 

[Darkhorse1201]

Re: OMC 3.8 V6 1983 Century Boat. Can I use car long block?

Stevieray - I stand corrected. You are 100% right that I should have said use a truck block not a car block. For the record the block I used was out of a Chevy truck so I have had no problems and had none with manifolds bolting up but that was on a 4.3 which are more common.
P.S. Like the moniker - hope its for my favorite guitar hero!!

 

[stevieray]

Re: OMC 3.8 V6 1983 Century Boat. Can I use car long block?

P.S. Like the moniker - hope its for my favorite guitar hero!!

Actually, my first name is Steve & since I do play, somebody called me Stevieray once & the name stuck. I do like the Vaughan stuff too.8)

 

[75GlastronMN]

Re: OMC 3.8 V6 1983 Century Boat. Can I use car long block?

My reseach shows that this is a chevy 3.8 (made from a 6 cyl 305 rather then a 6 cyl 350 which makes the 4.3)
It also looks like I could run a 4.3 but then I need to find a new intake as they are different froma 3.8 to 4.3.

I don't remember any chevy or GMC trucks ever using a 3.8. Only 2.8 and 4.3 V6's

 

[whywhyzed]

Re: OMC 3.8 V6 1983 Century Boat. Can I use car long block?

ElCamino/GMC Sprint was the only truck that used a 3.8.
Regardless, the car 3.8 (chevy 229) longblock is identical to OMC except for the camshaft and the core plugs. Even the heads and valves are identical.

4.3 Intake manifold same as 3.8 as long as both are pre-vortec.

I'd stay 3.8 and here's why:

4.3 2 BBL rated 175 HP
3.8 2BBL rated 170 HP

4.3 4BBL rated 195 HP
3.8 4BBL rated 185 HP

I also believe the width of the 4.3 head makes the exh manifolds sit a bit differently and exh hoses to the intermediate and thermostat hsg. would be out of alignment.

 

[75GlastronMN]

Re: OMC 3.8 V6 1983 Century Boat. Can I use car long block?

Sounds good. I think I will just run a 3.8 out of some GM car and just swap the cam.
Thanks for all the help!

 

[whywhyzed]

Re: OMC 3.8 V6 1983 Century Boat. Can I use car long block?

check your p.m.'s