GM Truck Club
THE PREMIER CHEVY TRUCK & SUV FORUM
Founded in 2004 ~ We're the #1 Chevy Truck & SUV Forum.
Silverado & Sierra | Tahoe & Yukon | Suburban & Yukon XL | SUV & CROSSOVER
Results 1 to 10 of 10
  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

    Default

    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

    Default

    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

    Default

    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.
    Christopher

    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 277K 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

    Default

    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

    Default

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

  7. #7

    Default

    with him having EFI (TBI) he should just have the in-tank electric fuel pump.

  8. #8

    Default

    Quote Originally Posted by Crawdaddy View Post
    with him having EFI (TBI) he should just have the in-tank electric fuel pump.


    That's correct. However, you should attempt to locate an engine that was from an '88-'95 to make it a "drop in" and '96-'99 if you don't mind swapping externals. There is a difference in the way the rear main seal is installed in the pre-1988 blocks that might cause a problem, IIRC.
    "It went together didn't it? Well then there has to be a way to take it apart!" - Me.

    Check out my image gallery HERE.



    "The true measure of a man is how he treats someone who can do him absolutely no good." ~Samuel Johnson (1709-1784)

  9. #9

    Default

    Quote Originally Posted by Crawdaddy View Post
    with him having EFI (TBI) he should just have the in-tank electric fuel pump.
    Should, but 87/88 model trucks were odd they had some old and some new parts and it wasnt always the same since they were the first year for GM's new platform and the last year of the old platform.
    Some of the heavier GM trucks of that era came from the factory with carburators and mechanical fuel pumps, some also came with external electronic pumps. He'll have to determine what he has on his truck.
    Some of the early generation TBI systems used a mechanical fuel pump before GM figured out their fuel starvation issues.

  10. #10

    Default

    Quote Originally Posted by tbplus10 View Post
    Should, but 87/88 model trucks were odd they had some old and some new parts and it wasnt always the same since they were the first year for GM's new platform and the last year of the old platform.
    Some of the heavier GM trucks of that era came from the factory with carburators and mechanical fuel pumps, some also came with external electronic pumps. He'll have to determine what he has on his truck.
    Some of the early generation TBI systems used a mechanical fuel pump before GM figured out their fuel starvation issues.
    Ah, I didn't realize they used mechanical fuel pumps on some TBI setups.

Similar Threads

  1. 5.3 motor swap
    By 03 SIERRA in forum GM Powertrain
    Replies: 0
    Last: 09-26-2012, 11:42 AM
  2. what motor should i swap in
    By john350 in forum Performance & Fuel
    Replies: 12
    Last: 12-21-2011, 06:52 PM
  3. motor swap - 350, 383
    By GMCZ71 in forum GM Powertrain
    Replies: 8
    Last: 08-10-2010, 07:10 PM
  4. motor swap
    By heavy chevy in forum Performance & Fuel
    Replies: 6
    Last: 06-30-2010, 06:22 PM
  5. Ls motor swap
    By ngchevy in forum Chevy C/K Truck Forum
    Replies: 1
    Last: 12-14-2008, 08:21 PM

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •