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Need help identifying GMC engine

Discussion in 'The Hokey Ass Message Board' started by willowbilly3, Aug 8, 2011.

  1. willowbilly3
    Joined: Jun 18, 2004
    Posts: 4,356

    willowbilly3
    Member Emeritus
    from Sturgis

    1955 or maybe 56 GMC farm truck. It says 300 on the grill and model is 303 on the id tag. ID tag also says 130 gross horsepower and 120 net horse power. It is headed to the crusher and I want to save it if it is a 270 or 302. How can I quickly identify the engine? thanks.
     
  2. 32Essex
    Joined: Oct 21, 2007
    Posts: 160

    32Essex
    Member
    from Texas

    Look beside the distributor and it should have 270 or 302 cast in the block.
     
  3. anteek
    Joined: Feb 27, 2009
    Posts: 394

    anteek
    Member

    On the right side of the block,by the dist. there is a flat, machined surface. This will have a ID code but more importantly, the engine size.
     
  4. RichFox
    Joined: Dec 3, 2006
    Posts: 10,020

    RichFox
    Member Emeritus

    yeah. First three numbers. Stamped not cast in mine
     

  5. 32Essex
    Joined: Oct 21, 2007
    Posts: 160

    32Essex
    Member
    from Texas

    Dam I hate old people, sorry I fucked up, it's been a while since I've seen one.
     
  6. willowbilly3
    Joined: Jun 18, 2004
    Posts: 4,356

    willowbilly3
    Member Emeritus
    from Sturgis

    OK, thanks. I will look tomorrow. Is it worth saving if it's a 248?
     
  7. Why not? If nothing else it has all the accesory stuff you can use for a larger GMC engine. If my memory is right, the following is correct:
    228 = smallest bore, same stroke as 248
    270 = same bore as 248, same stroke as 302
    302 = largest bore

    The 248 may be down a bit on cubes, but if it is good condition you could just run it. The other parts like bellhousing and flywheel could be useful as well. Pretty sure GMC has same bellhousing pattern as the 235/261 Chevy.
     
  8. Kinky6
    Joined: May 11, 2003
    Posts: 1,765

    Kinky6
    Member

    These sizes are all correct, but there are also two others in this line-up; a 236" and a 256". Pretty rare, I've only seen one of each, stamped numbers down by the distributer shaft, resting in junkyard GMC's, but they are listed in my motors manual. Don't recall how the bore/stroke relates to the other engines.

    Later, Kinky6 :cool:
     
  9. willowbilly3
    Joined: Jun 18, 2004
    Posts: 4,356

    willowbilly3
    Member Emeritus
    from Sturgis

    Thanks, it's a 248. I haven't had time to see if it will pop off yet but supposedly it was running 3 years ago. I bought the truck to save it from the crusher since it had a pretty decent set of 7.50x20 rubber that is getting a little hard to find. Will strip it of any good parts and let it continue it's way to the crusher.
     
  10. What did ya do with them parts??
     
  11. willowbilly3
    Joined: Jun 18, 2004
    Posts: 4,356

    willowbilly3
    Member Emeritus
    from Sturgis

    Engine was stuck. It all went to the crusher after the cab was parted out and the tires sold.
     
  12. 33-Chevy
    Joined: Nov 30, 2007
    Posts: 267

    33-Chevy
    Member

    If you ever see another one consider saving the oil pan, oil pump pickup and flywheel because they fit the 302 and big truck 270 and make it easier to install the big truck engines in pick up trucks and passenger cars.
     
  13. RichFox
    Joined: Dec 3, 2006
    Posts: 10,020

    RichFox
    Member Emeritus

    My first 270 was very stuck when I bought it in '77. Been outside in a junk yard, uncovered without a carburator for about 10-12 years. Very hard to get apart. Went 158 mph in my stock roof '32 Ford 5 window and still holds it's class record at El Mirage. Don't crush GMCs just because they are stuck. Flex a mussle
     

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