OMC 5.0 to Chevy truck 5.7 flywheel question

[Handegard]

Will the flexplate/flywheel interchange between a '94 350 and a '88 OMC 305?

I ask because I know Ford changed the balance of the crank from 28oz to 50oz at some point, and you have to swap the harmonic balancer and the flexplate, I don't want to run into any issues like that with the Chevy motor...

I've read about freeze plugs, cams, and using marine grade parts for this swap, and I'm prepared to do all that. But I'm a Ford guy, so my knowledge of Chevy motors is pretty limited...

 

[cr2k]

Re: OMC 5.0 to Chevy truck 5.7 flywheel question

You will have to look at the real main seal. ( I am not sure of the change dates) but if they both have the one piece rear main seal I would say yes.

 

[Handegard]

Re: OMC 5.0 to Chevy truck 5.7 flywheel question

Hmm... I will have to poke around on my Chevy forums to see if I can find out from some casting numbers...

See, the point being to avoid taking the 302 out at all if they can't be switched... I'll be in a foul mood if we pull it out and it hast to go back in...

Thanks though, it gives me one more thing to ask the chevy guys..

 

[Bondo]

Re: OMC 5.0 to Chevy truck 5.7 flywheel question

Ayuh,... If you can answer 2 questions, You'll know the answer about the flywheel swap...

If the 305 Is in fact a 1988, not an 86 or Earlier, the crankshaft bolt pattern will be the same...
Next,... Are the Starters the Same bolt pattern,..?? Staggered,..??
If so, both will be for 14" flywheels,+ you're Good to go...
If the 305 has the Straight across starter bolt pattern, It's got a 12" flywheel...
If the 350 block is drilled/ tapped for that pattern, You're still good to go...

 

[cr2k]

Re: OMC 5.0 to Chevy truck 5.7 flywheel question

I believe it '87 when they went to one piece rear main seals. So the '88 boat may or may not have a one piece rear main seal. Being that clost to change date you need to do a SN search.

 

[Alpheus]

Re: OMC 5.0 to Chevy truck 5.7 flywheel question

Just look at your valve covers. If the 4 bolts holding them on are down the center of the valve cover its a one piece rear main seal. If it has 4 bolts on the corners its a two piece rear main seal...