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1957 GMC 100 - 270 Engine

Discussion in 'The Antiquated' started by David Whtiman, Jul 10, 2019.

  1. David Whtiman
    Joined: Mar 24, 2019
    Posts: 1

    David Whtiman

    First thanks for having this forum and thanks in advance for any advice you can give.

    and ..... If you have a 270 I could be interested in buying it.

    I have a 57 GMC 100 step side (originally a 3 on the tree) that a kid back in the 90's transplanted a 230 and Turbo Hydromatic 350 into by torching the cross member out and adding some modified motor mounts. I would like to get this rig back to close to original and use it as a driver, vanity truck for around my area. I've managed to find a cross member, and a 3 speed and now I need to get a 270. These are from a parts dealer in Marysville, Washington. I'm dreaming of having a numbers correct engine but have found a 1953 270 that I can up pick up for a few hundred. Will this fit my truck? It came out of a fire truck. supposed to run.

    I've used this page to research casting numbers
    Now I have what is a simple question about casting numbers... Are the numbers listed in the table the starting numbers and what falls after that and before the next years designation valid? In other words will the number be different but be between the two? See these examples:
    The list calls out these for 1957 GMC 270 Engine Casting #'s but they cross multiple years

    I've taken this 2136477 to be a 1953

    Someone else had one with this number - 248260112.... Is this a matching numbers correct for my rig?

    Thanks again,
  2. the first numbers stamped next to the dist on a pad denote engine size. 228 or 248 & 270 and every once in a while a 302. I have a 248 in my hoard. the last you mentioned is likely a 248. the GMC 6 is longer than a chevy engine. you need the correct GMC radiator to make everything work properly.
  3. jimmy six
    Joined: Mar 21, 2006
    Posts: 4,655

    jimmy six

    Military blocks are different in the way they mount so the holes on the side of the block are not all the same.There were military 270's as well as the more common 302.
    I'm guessing a 55-59 Chevrolet 6 bellhousing will fit the cross mount you have found. Should be ez to find.
    Some front mounts look like saddles which have 2 bolts on either side right at the front of the block and others mount to the plate which goes on the engine first before the cam goes in. That one is more common on earlier models.
    Just thing to look at. I would advertise for someone doing a V-8 swap into a 55-59 for the correct parts. Good Luck

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