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1972 Combat Pushrods

Discussion in 'Norton Commando Motorcycles (Classic)' started by cbacejr, Oct 8, 2014.

  1. cbacejr

    cbacejr

    Joined:
    Apr 8, 2014
    Hi All,

    I'm rebuilding a 1972 Combat engine and have been told that I need pushrods .040 shorter than standard. I call a few places and can't seem to find any.

    Can anyone help with this?

    Thanks,
     
  2. kraakevik

    kraakevik

    Joined:
    Oct 12, 2009
    I've seen many references advocating the removal of .040" of material from the aluminum pushrod barrels to restore the rocker geometry that was compromised when Norton shaved .040" off the head face to raise compression for Combat engines. I've not seen modified or newly manufactured shortened pushrods offered for sale



    Tim Kraakevik
    kraakevik@voyager.net
     
  3. dynodave

    dynodave

    Joined:
    May 28, 2003
    "I'm rebuilding a 1972 Combat engine and have been told that I need pushrods .040 shorter than standard"


    Hasn't anyone also told you to also take 1/2 of the extra lift from the combat cam lobes?
    exh .341-.330 = .011
    int .387-.330 = .057

    why wouldn't that count too?
     
  4. L.A.B.

    L.A.B. Moderator VIP MEMBER

    Joined:
    Nov 20, 2004
  5. hobot

    hobot

    Joined:
    Oct 19, 2005
    Its been found the valve train mass on the cam side does not matter much compared to valve side of rockers and valve control was more important than cam side mass, so the RGM steel kit is best way to go and diddle your Combat spot on by trial error creeping up on it, rather than trust some funny math, though that should put it closer right than factory Combats - which don't wear out valve train any more than spot on geometry but may valve float sooner.
     

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