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59ab flathead piston issue

Discussion in 'The Hokey Ass Message Board' started by BillyBobsSpeedShop, Sep 13, 2011.

  1. BillyBobsSpeedShop
    Joined: Jan 6, 2008
    Posts: 522


    I have a 59ab flatty that came out of a running welder. I witnessed the motor running and it seemed to run fine. I pulled the intak and the valve train was really clean. I then pulled the heads off and all the pistons looked good except for one. I notice what appears to be a chip on the edge of the RH side read piston. It looks to be just on the edge of the piston. The bores feel smooth throughout the engine. I looked at the bottom of the head and there was no place the piston hit, no marks or anything?

    I looked at the valves and they all seem good and there was only carbon build up on the piston and the adjacent valve. There was no piston fragments. The mark doesnt look to be fresh and looks out of place, could this flathead have had this mark in it this whole time and run fine? The motor is in good shape and there is no cracks that I have found in the block. I was originally going to just slap on a pair of edelbrock heads and edelbrock intake that I have and run the engine and not sure if I should now.

    I called a couple guys today and last night and one is a flathead builder and he said it should be ok from what I was describing to him but he hasnt seen it. He said if it doesnt appear to have hit anything then it may be ok. Another guy said I need to replace the piston, I respect both of their opinions and am taking both into consideration. I am not trying to build a stump puller just want a nice cruiser but would hate to have major problems down the road. I was told the engine never gave he guy a problem and he had never taken it apart, and from me taking it apart it seemed very tight.

    All suggestions will be very appreciative. I would like to to just run it as it but not sure. Thanks
  2. Atwater Mike
    Joined: May 31, 2002
    Posts: 10,705

    Atwater Mike

    A cardinal rule of engine assembly is close inspection of pistons.
    Proposed feet per minute of travel would dictate that their condition be excellent, and held to one standard. (this includes all of them)

    If you are 'not sure', just imagine that box checked on a Quality Control build sheet.
    Balancing them is the final step...
  3. JohnEvans
    Joined: Apr 13, 2008
    Posts: 4,883

    from Phoenix AZ

    A picture would help ! Some pistons have a notch on one edge to show the direction for correct fitment in the engine.
  4. BillyBobsSpeedShop
    Joined: Jan 6, 2008
    Posts: 522


  5. 1950ChevySuburban
    Joined: Dec 20, 2006
    Posts: 6,188

    Member Emeritus
    from Tucson AZ

    That's trash, sorry.
    When in doubt, throw it out as Mom says.
  6. Jimmy2car
    Joined: Nov 26, 2003
    Posts: 1,707

    from No. Cal

    I'd replace it and check all the others. It could be that the piston shown has broken rings.
    Just my opinion.
  7. BillyBobsSpeedShop
    Joined: Jan 6, 2008
    Posts: 522


    Im going to pull the piston today.
  8. 42hotrod
    Joined: Nov 3, 2005
    Posts: 811

    from S.E. Idaho

    Fuck it, run it! hahaha
  9. rotorwrench
    Joined: Apr 21, 2006
    Posts: 633


    If hot gasses start passing by that spot when the ring gaps line up there, it will burn little bits of the cylinder wall away and that's even if the ring is not broken. Some folks say the rings don't turn in the grooves. They haven't met Murphy yet.

    I have a block with some burned out grooves in the wall where a ring broke so I know it can happen. The damn thing would still pull near 30 psi of compression even with the compression gas going through there.
  10. wise decision....has definite damage and won't heal up itself.
  11. 42hotrod
    Joined: Nov 3, 2005
    Posts: 811

    from S.E. Idaho

    You all realize I was kidding, right? :D
  12. Heo2
    Joined: Aug 9, 2011
    Posts: 661


    Looks like you have broken rings in the left upper corner
    in the pic you can see a black spot on top the cylinder
    wall where the ring dont have scraped the soot away
    the probabel cause to the damage is probably .......
    spark knock, pinging ore what ever ts caled in english
  13. 36tbird
    Joined: Feb 1, 2005
    Posts: 1,084


    Billy, I'm not trying to sound like a butt head here, but flatheads are numbered 1 to 4, front to rear on the U.S. car passenger side, 5 to 8, front to rear U. S. car driver's side. You people "down under" will have to figure it out on your own.:D

    Do you have any buddies with some like size used pistons? I'd replace that one and then run it. You can worry about balancing and all that on a complete rebuild.
  14. BillyBobsSpeedShop
    Joined: Jan 6, 2008
    Posts: 522


    I pulled the piston with ease and the first ring in the piston was bad. So I am needing a STD piston for my 59ab flatty if anyone has one laying around
  15. PM me I should have one laying around send it to ya for the shipping.........
  16. Ford Guy
    Joined: Jan 9, 2010
    Posts: 53

    Ford Guy

    Are you kidding?! Shouldn't be more than a #10 envelope and a postage stamp!

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