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Technical pontiac 8

Discussion in 'The Hokey Ass Message Board' started by Redneck7.3, Aug 12, 2018.

  1. Redneck7.3
    Joined: Jul 19, 2018
    Posts: 7

    Redneck7.3

    Can anyone tell me if Pontiac used basically the same block ? I need to bore mine .030. I can only find pistons that are .060 over. I know that they had a 3 1/4" bore in 1940 and in 1949 it was 3 3/8 . The .060 would be about 3 5/16 (3.310) It sounds like it's OK but before I have it bored I'd like more info.
     
  2. Have you checked Egge in S.F.S., CA?
     
  3. KJSR
    Joined: Mar 7, 2008
    Posts: 1,948

    KJSR
    Member
    from Utah
    1. Utah HAMBers

    Hi I have a XXXX Pontiac block.. what size is it safe to bore to?
     
    Bandit Billy and wvenfield like this.
  4. Redneck7.3
    Joined: Jul 19, 2018
    Posts: 7

    Redneck7.3

    Yes . I've checked every place recommended on the Pontiac website , e-bay, amazon,
     
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  5. KJSR
    Joined: Mar 7, 2008
    Posts: 1,948

    KJSR
    Member
    from Utah
    1. Utah HAMBers

    Sounds like you have a handle on it.
     
  6. There has to be someone who has a smaller overbore than that. That sounds like that could make it the last overbore before you would end up sleeving that block.
     
  7. The inline eight is basically the same block from the 30s through 1954, but there are various upgrades through the years.

    I'd be very surprised there are no .030 pistons.
     
  8. Redneck7.3
    Joined: Jul 19, 2018
    Posts: 7

    Redneck7.3

    I've been all over the internet for two weeks. Someone I called has a lot of different sizes of aluminum coming from Europe in Sept sometime .
     
  9. Redneck7.3
    Joined: Jul 19, 2018
    Posts: 7

    Redneck7.3

    I will follow all leads you guys give me that I haven't already.
     
  10. Redneck7.3
    Joined: Jul 19, 2018
    Posts: 7

    Redneck7.3

    If stock bore is 3.250 and the '54 engine is 3.375 if I go to 3.310 why won't it work & still be able bore again. Rustynewyorker says the blocks are basically the same .Must be a lot of straight 8's being rebuilt this year.
     
  11. Desmodromic
    Joined: Sep 25, 2010
    Posts: 76

    Desmodromic
    Member

    I don't know the answer to your specific question, but be wary of the phrase "basically the same ......". Generally, when a manufacturer increases bore size, new casting patterns are made. You can't make a 400 cid Chevvy with a 265 block, boring bar, and new crank.
     
  12. Redneck7.3
    Joined: Jul 19, 2018
    Posts: 7

    Redneck7.3

    I understand. That's why i'm asking questions. Mine is 1948. I wondered if they cast the block heavier for 1949 to get 268 cu. in.
     
  13. firstinsteele
    Joined: Jun 13, 2013
    Posts: 676

    firstinsteele
    Member

    Why not sonic test the cyl walls and bore all the way if they will allow? If pin height and other specs allow.

    You can get whatever size piston you want from the "racing" piston makers.

    Ben
     
  14. Redneck7.3
    Joined: Jul 19, 2018
    Posts: 7

    Redneck7.3

    I found a set of unfinished pistons here in Michigan (Northwestern Auto Parts) and they were able to grind them .030 over so I think I am ready to go. THANK YOU for your input And getting me to at least to think outside the box .
     

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