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marine 401 nailhead

Discussion in 'The Hokey Ass Message Board' started by chopt31, May 25, 2013.

  1. chopt31
    Joined: Dec 1, 2008
    Posts: 1,147


    I ran across a guy that has 2 401's, both from boat, 1 is standard, the other is reverse rotation, what all is involved in changing rotation? thanks
  2. mgtstumpy
    Joined: Jul 20, 2006
    Posts: 8,720


    I thought it was just the camshaft, possibly distributor gear and starter motor?
  3. Build a twin-engined FED with 'em.....................

  4. And race it at the Meltdown!!! :D

  5. 48 Chubby
    Joined: Apr 29, 2008
    Posts: 1,014

    48 Chubby
    Member Emeritus

    On MOST engines just the cam shaft, starter, and water pump. I have not worked on a marine Buick however.
  6. Rusty O'Toole
    Joined: Sep 17, 2006
    Posts: 9,493

    Rusty O'Toole

    I would check the pistons too. Piston pins are normally offset to reduce piston slap. They would have to be offset the other way, or the pistons put in backwards in a reverse rotation situation. I don't know this for sure but it seems logical.
  7. That was my first thought too...
  8. slimpick
    Joined: Aug 4, 2008
    Posts: 97


    Pistons are the same. I did a reverse rotation corvair in the past.

    The distributor gear could be cut the "opposite" way. That way the cam puts thrust on the distributor gear in the correct direction.
  9. Dan Timberlake
    Joined: Apr 28, 2010
    Posts: 1,307

    Dan Timberlake

    "That way the cam puts thrust on the distributor gear in the correct direction."

    And keeps the firing order right, and prevents the centrifugal advance from becoming centrifugal retard.
  10. mustangmike6996
    Joined: Apr 7, 2013
    Posts: 147

    from the D

    At a bare minimum... you have a 401 nailhead block as far as the reverse rotation goes lol.

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