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  1. #1

    Default Whats the Difference between 70's and 80's 350ci

    I just bout a 86 Sierra that has a 70 something 350. He was not sure which year so I would like to know what big changes I can expect.

  2. #2


    Some of the Mid 80's V-8's are all ready to accept roller cams (mid 80's on should have the holes for the bolts that hold the plate down that keep the roller lifters in place). Also some time between 85 and 88 they switched over to a 2 piece rear main. If you have a 70's 350 in it you're lucky they are cheaper to tinker with and rebuild if you need to because the parts are so much more common. basically a 70's 350 is basically the same as a late 60's 350 and an early 80's 350. But the two piece rear main is the big difference...

  3. #3

  4. #4
    Jr. Mechanic
    Join Date
    Apr 2010
    Ortonville MI


    80s smog heads and early 70s wherent if it has 70s heads on it.

    07 NBS Crew cab SLT 4x4

  5. #5
    Jr. Apprentice
    Join Date
    Aug 2010
    Channahon, IL


    Actually, in '87 GM went to a one-piece rear main. Older two-piece blocks can be converted to this style if desired, but it isn't recommended since that leads to a parts chase. But, no worries. A Generation 1 350 block is a Generation 1 350 block. The newer ones may not have the holes drilled for a mechanical fuel pump, but they can be.
    440 HP 383 + 150 shot = fun weekend!

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