doing a GM 5.0 to 5.7 ??
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doing a GM 5.0 to 5.7 ??

  1. #1
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    Default doing a GM 5.0 to 5.7 ??

    have an OMC Cobra with GM5.0 and considering doing a 5.7 since I have to replace the block on the 5.0 anyways.

    Question is if this is a strait up interchangeable swap. If not what doesnt interchange?

    Thanks!
    77' Spectra BBF460

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    Member Dano214's Avatar
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    It should all be the same. If im not mistakin the block is the same its just smaller displacement

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    Senior Member EVILFORCE's Avatar
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    Heads are different. Use 350 heads.

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    Senior Member GT Jets's Avatar
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    Plan on buying a bigger pitch prop... The final gear ratio you have is more than likely a 1.50:1 and a 5.7 (260HP) came with a 1.41:1...

    The ratio in in the upper GC, should have 21 teeth on the drive and 16 teeth on the driven for the 5.7L...

    Most everything else will work fine. The heads can be used from the 305 depending on deck height.
    GT


    Quote Originally Posted by Quickjet View Post
    Put a 300 on the back of it, Flywheel it and a nosecone. $15,000 later you'll have a 65 mph pile of shit......

  7. #5
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    Thanks for the information guys!! I found a exact match 305 from a kinda local shop. Im thinkin' Ill swap that in there and get out of this thing. =) Found a deal on a sweet lil Campbell vdrive.

    Thanks again guys!!
    77' Spectra BBF460

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