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  1. #1

    Default Motor swap, need help

    Im in the process of swapin out the motor on my 88 gmc heavy half ton, its a 350 5spd. and has a ton of blow by, and leaks about a quart from the main seal every 10min at idle. im looking for a motor for it, and have had no luck with a used tranny, but i need to know if anyone knows if its a four or two bolt main? been a while since i tackled a motor swap. thanks guys.

  2. #2


    Without casting numbers to go by anything at this point would be a guess.
    And my guess would be 2 bolt main since trucks of that vintage normally didnt get the 4 bolt main unless they were 3/4 or 1 ton or had a factory performance package of some type.

  3. #3


    can i find out with casting numbers? i know it was the first year of the efi, ive only ever done 2 bolt main motors. but i found a motor for it from a 90 thats a 4 bolt main.

  4. #4


    Sounds like you found a winner. Whether it's a 2 bolt main or 4 bolt main doesn't matter installation-wise. I agree with Tim that it's most likely a 2 bolt main if the motor has never been swapped. Also, the bottom ends of the 350 have been the same pretty much through their entire run if I remember correctly, so as long as you don't need a manual fuel pump provision (it sounds like you don't) then any 350 block should work.

    1991 Chevy Suburban 1/2 ton 2WD w/ chevy SBC 350-3/4 ton drivetrain upgrade w/4.10 gears 200K miles
    2005 Saturn ION-2 Stock 265K miles
    1982 Bronco, 1993 Bronco (sold), 1971 M35A2 Deuce and a Half

    There are 10 kinds of people, those who understand binary, and those who dont...

    Remember kids, the only difference between screwing around and science is writing it down- Adam Savage

  5. #5


    So installation will still work and it will run fine?????? the motor i found is a 4bolt. I just dont want to have to do this again.

  6. #6


    Yep, like Christopher said the big difference will be fuel pump, now would be a great time to put an electric one on anyways.

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