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5.7 engine coupler question

fallonboy

New member
5.7 Engine coupler question.
New guy here. Got an older boat with a 5.7 engine 1-piecerear main seal. OMC Cobra outdrive. I am replacing the engine with a Mexicrate5.7 engine 2-piece rear main seal. I do not want to return this engine. I wouldlike to make it work.
The 5.7 1-piece rear main seal engine takes coupler 984290.
The 5.7 2-piece rear main seal engine takes coupler 76850A2which is 1 ½ inch shorter in length…..I think. I have not ordered it yet.
Question: will the same drive shaft work? Is the some sort of a modification kit avail?

Thank you




 
Thanks Chris - we are changing the FW and coupler. If a spacer is needed we'll fashion one from the FW end of an old crankshaft....at this point.

Thanks Ricky - the boat belongs to my neighbor. It has lots of repairs done to it. My neighbor thought all chevy 350' are equal. I think he is from Oregon.
 
Thanks Rick - the boat belongs to my neighbor. It has lots of repairs done to it. My neighbor thought all chevy 350' are equal.


The SBC 5.7L engines are somewhat equal in that they all share the 4.000" bore and the 3.480" stroke.
But..... there are many subtle changes that took place throughout the years.
Light cylinder head castings -vs- heavy castings. Different strength crankshafts. Varying Nickel content in the cylinder block and head castings. Cylinder head runner volume changes.


For the SBC Marine enthusiast, in-compatible piston profile and cylinder head combustion chamber volume selections (and visa-versa) often get us into trouble.



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