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Hot Rods valve seat has come loose in my flathead

Discussion in 'The Hokey Ass Message Board' started by DjNeil, Mar 10, 2016.

  1. DjNeil
    Joined: Dec 29, 2011
    Posts: 210


    Ive lost compression in a cylinder and turns out it is a valve seat.I'm hoping i can replace it in situ by peening it into position and lots of lapping in after.i'm not sure how a new seat arrives,does it already have the angles cut into it.I can see a problem with alignment but maybe possible
    my other option maybe to kill the cylinder by taking out the exhaust and inlet lifter so the valves shut,take off the HT lead off and,hey presto,i've got a 7 cylinder flathead until i can tear down the motor to a block.This seems a lot to do for one valve seat
    any thoughts appreciated

  2. alchemy
    Joined: Sep 27, 2002
    Posts: 16,705


    The new seat (no, you probably won't be able to save that seat) will need grinding. You can do it with all the rest of the engine assembled. Probably only been done a million times. But you will need to use lots of towels and vacuuming to keep the grit out of the rest of the engine.
  3. woodiewagon46
    Joined: Mar 14, 2013
    Posts: 1,817

    from New York

    I wonder what the valve guide looks like. You might consider pulling the intake manifold. You are right about the alignment, I would think the guide would center the valve more than it is.
  4. Back in the '60's I was driving an old truck with a Hercules flathead gas motor. Lost a valve seat on the freeway. My boss found a guy that would come out to the truck and put a new seat in it right there along side the freeway. Sure enough, he had everything he needed to do the job. A few hours later, I was on my way.

  5. Mr48chev
    Joined: Dec 28, 2007
    Posts: 28,779


    The valve may be bent causing the head to be off center. At any rate you will have to take the intake off and take that valve out to replace the valve seat. Once you have it torn down it should be a reasonably simple for an automotive machine shop to do. You could tow it to them, have them replace the seat and grind the valve and seat and tow it home and install the head and intake.
  6. greg32
    Joined: Jun 21, 2007
    Posts: 2,080

    from Indiana

    H & H uses a product called Seal-Lock to set valve seat.
  7. DjNeil
    Joined: Dec 29, 2011
    Posts: 210


    can't seam to find seal lock
  8. lodaddyo
    Joined: May 5, 2002
    Posts: 1,202


  9. 54fierro
    Joined: Jul 6, 2006
    Posts: 493

    from san diego

    I had the same think happen on an OT car recently. When I took the head in I overheard them ordering the seat as a +1 then the machinist said "get a +2".

    Sounds like there are oversize seats available. Don't know if it's a DIY job though.

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