1986 4.3 OMC engine swap to 1986 5.0 Volvo

[Scottyd2002]

I have a 1986 Crstliner with a 4.3 OMC outdrive.
Can I swap out the 4.3 for a 1986 5.0 w/Volvo without changing the outdrive on my Crestliner?

 

[Scott Danforth]

Welcome aboard

you can, however the gear ratio would be wrong going from a 4.3 to a 5.0, and you will have to move your front motor mounts, possibly doing a bit of fiberglass work.

make sure both motors are indeed 1986, as the 1985 and older motors have a 2-piece RMS crank and 1986 and newer are 1-piece. this is to make sure your coupler works

you will also need to figure out the exhaust going from brand A to Brand B and getting the OMG Y-pipe to work with other manifolds

is your 31 year old boat in sound structural shape?

 

[Bondo]

I have a 1986 Crstliner with a 4.3 OMC outdrive.
Can I swap out the 4.3 for a 1986 5.0 w/Volvo without changing the outdrive on my Crestliner?

Ayuh,..... Welcome Aboard,.... In theory, it oughta be a plug, 'n play, after ya possibly move the front motor mounts,...
'n the gear ratio will be off abit, but hopefully, a bigger prop oughta be able to fix that,... depends on the pitch it's spinnin' with the 4.3l,...
The Big But, is,.....
'86 was the transition year for Chevy crankshaft bolt patterns,...
If both are 1 pc. rear main seal, No problem,... or if both are the ole 2 pc. rear main, it Could make a difference,....