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Max overbore on a 303 Olds?

Discussion in 'The Hokey Ass Message Board' started by drag_punk, Dec 17, 2011.

  1. drag_punk
    Joined: Mar 6, 2001
    Posts: 99

    drag_punk
    Member

    I think that covers it. I have one that I just dissassembled after years of sitting outside, block seems okay but I know it will take a fair amount to clean up the bores.
     
  2. 302GMC
    Joined: Dec 15, 2005
    Posts: 6,817

    302GMC
    Member
    from Idaho

    Those blocks were bored 3/16" over with no problems back in the old days ...
     
  3. GOATROPER02
    Joined: Mar 22, 2006
    Posts: 2,059

    GOATROPER02
    Member
    from OHIO

    If you ever sonic checked one you would never bore one 3/16


    .125 over or

    3.875 to 324 bore size is max

    Tony
     
  4. Don's Hot Rods
    Joined: Oct 7, 2005
    Posts: 8,319

    Don's Hot Rods
    Member
    from florida

    I was just reading an old hot rod magazine last night and there was a dragster that had a blown 371 overbored 3/16 to 406 cubes. Were the cylinders thicker on those than the old 303's?


    Don
     

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

    willowbilly3
    Member Emeritus
    from Sturgis

    If it was a dragster they might have cemented the block.
     
  6. drag_punk
    Joined: Mar 6, 2001
    Posts: 99

    drag_punk
    Member

    Cool, .125 is what I thought too, just wanted to confirm that. Thanks Tony.
     
  7. GOATROPER02
    Joined: Mar 22, 2006
    Posts: 2,059

    GOATROPER02
    Member
    from OHIO

     
  8. RichFox
    Joined: Dec 3, 2006
    Posts: 10,017

    RichFox
    ALLIANCE MEMBER

    In the time when 303s cost $25 at the junk yard. When you couldn't get a free one. We regularly went to 3 15/16. I had one. Never any problems. But your water jackets have had another 50 some years to rust. And the extra inches won't really be noticeable. Unless it's a race car.
     
  9. falcongeorge
    Joined: Aug 26, 2010
    Posts: 18,341

    falcongeorge
    Member
    from BC

    The answer to this question is simple. Haul it down to your machinist, and have it sonic tested.
     
  10. drag_punk
    Joined: Mar 6, 2001
    Posts: 99

    drag_punk
    Member

    I probably won't even go .125 but I will if I have to. I'll only bore it enough to clean up the rust. This motor was seized, I'm not after cubic inches just want it cleaned up.
     
  11. GOATROPER02
    Joined: Mar 22, 2006
    Posts: 2,059

    GOATROPER02
    Member
    from OHIO

    Call me
    I can help you with pistons and rings...Pistons are easy in any bore size needed....The only thing we need to be careful of is ring selection(sizes and widths availablity)

    Tony
     

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