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  1. #1

    Default 5.7 engine coupler question

    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 ˝ 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





  2. #2
    Join Date
    Mar 2009
    Location
    Portland, Oregon,
    Posts
    9,194

    Default Re: 5.7 engine coupler question

    Why install an incorrect year model engine if it would create the need for an "iffy" modification ?



    .
    Rick ... aka Ricardo..... AQ series Volvo Penta repair
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP's

    Please... no PMs! Post your questions on the forum.

  3. #3
    Join Date
    Sep 2010
    Location
    Jersey Shore
    Posts
    4,635

    Default Re: 5.7 engine coupler question

    Flywheel and coupler need to be changed.
    Chris
    Dockside Marine Services
    Jersey Shore.
    Mercruiser/Mercury Certified
    Let the insanity begin.

  4. #4

    Default Re: 5.7 engine coupler question

    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.

  5. #5
    Join Date
    Mar 2009
    Location
    Portland, Oregon,
    Posts
    9,194

    Default Re: 5.7 engine coupler question

    Quote Originally Posted by fallonboy View Post
    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.



    .
    Rick ... aka Ricardo..... AQ series Volvo Penta repair
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP's

    Please... no PMs! Post your questions on the forum.

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