4.3 omc engine

[prospector65]

I have a 4.3 omc engine with a cracked block. Can I use any gm 4.3 block to replace it? The one I have is carbureted but they are hard to find in wrecking yards although there are plenty of fuel injected engines available. Would the blocks be the same so I could use my intake manifold, heads, and exhaust manifolds?

 

[Howard Sterndrive]

Re: 4.3 omc engine

generally, if you get a truck 4.3 the same year as your boat engine, they are pretty similar. Get the Pioneer brand Brass core plug kit for a chevy small block and then swap all the bolt on stuff over from your motor including ignition and fuel system.

If your engine is a 1985 or 1986 with a Cobra drive, you will need additional parts (flywheel, coupler)
If your drive is a 1985 4.3 stringer, you'll need a 1985 or 86 4.3 pre-rear main seal changeover motor.

 

[prospector65]

Re: 4.3 omc engine

generally, if you get a truck 4.3 the same year as your boat engine, they are pretty similar. Get the Pioneer brand Brass core plug kit for a chevy small block and then swap all the bolt on stuff over from your motor including ignition and fuel system.

If your engine is a 1985 or 1986 with a Cobra drive, you will need additional parts (flywheel, coupler)
If your drive is a 1985 4.3 stringer, you'll need a 1985 or 86 4.3 pre-rear main seal changeover motor.

This is an engine of unknown vintage bought on ebay and used in a boat I built. That is the reason for my query.

 

[Howard Sterndrive]

Re: 4.3 omc engine

This is an engine of unknown vintage bought on ebay and used in a boat I built. That is the reason for my query.

ok, but this is the OMC section, so if you have an OMC drive use the model and year of that in my reply above to figure out what year engine you need.

 

[prospector65]

Re: 4.3 omc engine

ok, but this is the OMC section, so if you have an OMC drive use the model and year of that in my reply above to figure out what year engine you need.

I do not have an OMC drive. This is a boat that I built and used the omc engine to power a jet drive. There is not a drive related problem here. All parts needed will be exchanged from one block to another, I just need to know if parts like intake, heads, etc. will fit on a automotive engine block from a fuel injected vehicle. Is there a difference in the engine blocks from a carbureted engine to a fuel injected one?

 

[Bondo]

Re: 4.3 omc engine

I do not have an OMC drive. This is a boat that I built and used the omc engine to power a jet drive. There is not a drive related problem here. All parts needed will be exchanged from one block to another, I just need to know if parts like intake, heads, etc. will fit on a automotive engine block from a fuel injected vehicle. Is there a difference in the engine blocks from a carbureted engine to a fuel injected one?

Ayuh,.... The 4.3l motors have changed, quite abit over their production life,...

Ya gotta exactly match the production vintage of yer donor motor, with yer junkyard motor,...
that said, Nope, No difference 'tween the Long Blocks, at All,...

Boat motors use brass core plugs insteada steel, so they don't rust out,..

Does this OMC donor motor have the 1 piece exhaust manifolds,..??
If so, they're Junk, 'n will kill the motor ya build,...
Get a set of 2 pc. Manifolds, 'n Risers,...

 

[Howard Sterndrive]

Re: 4.3 omc engine

you're going to need to get some numbers off the motor and google them to find out the year. Crank coupler bolt patterns and flywheels changed, intakes changed.

 

[prospector65]

Re: 4.3 omc engine

you're going to need to get some numbers off the motor and google them to find out the year. Crank coupler bolt patterns and flywheels changed, intakes changed.

Thanks everyone for the info. I'll have to do more research or just try a different engine. I may even replace the transom and go with outboards.