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Pushrod diameter ?

Discussion in 'Norton Commando Motorcycles (Classic)' started by Fast Eddie, May 17, 2019.

  1. Fast Eddie

    Fast Eddie VIP MEMBER

    Joined:
    Oct 4, 2013
    Could someone please tell me the outside diameter of a stock Commando aluminium pushrod ?
     
  2. L.A.B.

    L.A.B. Moderator VIP MEMBER

    Joined:
    Nov 20, 2004
    I measured four which varied from 9.51 to 9.58mm.
     
  3. Fast Eddie

    Fast Eddie VIP MEMBER

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    Oct 4, 2013
    Thanks a lot LAB, that’s exactly what I needed.
     
  4. baz

    baz VIP MEMBER

    Joined:
    May 26, 2010
    Why do you need the info Eddie? Are you having some special ones made?
     
  5. Fast Eddie

    Fast Eddie VIP MEMBER

    Joined:
    Oct 4, 2013
    The inlet pushrods on the 920 I’m building are rubbing against the inside of the head.

    I wanted to ascertain if it is my pushrods that are too fat.

    They are not, so I’ve got to get fiddly and remove some material from in there it seems.

    But I’ve no idea why !!
     
  6. baz

    baz VIP MEMBER

    Joined:
    May 26, 2010
    Maybe something with the rockers?
     
  7. dynodave

    dynodave

    Joined:
    May 28, 2003
    Stock 1S cam?
    If hot rod cam then you may well have rubbing on the exhaust side.
    As the (shorter) rocker goes up it also pulls the pushrod toward the front of the engine.
    This is all well known (by some) and is why early barrels and head gaskets were "upgraded" to allow the forward swing.
    88 vs 88SS and 99 vs 99ss, the SS engines having the higher lift SS cam.

    Dommy SS Barrels
     
    Last edited: May 17, 2019
    robs ss likes this.
  8. gortnipper

    gortnipper VIP MEMBER

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    Nov 11, 2013
    JS3 and Maney barrels IIRC.
     
  9. Fast Eddie

    Fast Eddie VIP MEMBER

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    Oct 4, 2013
    It’s a Maney cam and Maney barrels. Rubbing is up in the head though, so nothing to do with barrels or head gasket.

    My issue is actually the inlets... not exhausts.

    Could be a rocker issue, I have some others so will check.

    I sincerely hope it’s not the rockers though, they are brand new AN rockers, lightened and polished by Pete Lovell... probably the most expensive Commando rockers in history...!
     
  10. blaisestation

    blaisestation

    Joined:
    Apr 10, 2008
    Pickies ? [please]
     
  11. Fast Eddie

    Fast Eddie VIP MEMBER

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    Oct 4, 2013
  12. blaisestation

    blaisestation

    Joined:
    Apr 10, 2008
    your shiny rockers .
     
  13. Fast Eddie

    Fast Eddie VIP MEMBER

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    Oct 4, 2013
    Oh these! I am pleased to confirm that these are NOT at fault (phew)!
    2E8792F9-AF96-4048-B027-BF02B6F4CB3D.jpeg F7D699D7-781E-4804-955B-DA3F698F34A8.jpeg
     
    gortnipper and MichaelB like this.
  14. Fast Eddie

    Fast Eddie VIP MEMBER

    Joined:
    Oct 4, 2013
    Ok, basically, it looks like the head was not machined correctly all those years ago (Friday afternoon job)?

    The pushrod tunnels were kinda off centre, to tight for the inlet on one side and the exhaust on t’other.

    I got a tools down inside and relieved quite a lot of material. Doesn’t look as nice as if I’d got it set up on the mill like you flash lads, but it’ll work!
     
  15. blaisestation

    blaisestation

    Joined:
    Apr 10, 2008
    oh err [drool],not long now eh ?
    Id be as chuffed as a chuffed persons chuffed bits.
     
  16. Fast Eddie

    Fast Eddie VIP MEMBER

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    Oct 4, 2013
    I will be when it’s running and hoofing out a gazillion BHP !!
     
    blaisestation likes this.
  17. baz

    baz VIP MEMBER

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    May 26, 2010
    Those rockers look like they'll keep your valves under control up to 13000 rpm I reckon
     
  18. Fast Eddie

    Fast Eddie VIP MEMBER

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    Oct 4, 2013
    They are nice!

    And the pushrods from Ken (LCR) are lovely n light too.

    It ain’t gonna be a rev monster, but it’s nice to know the valve train will be nicely under control.

    Assuming I ever get it finished... it’s nearly 3 years since a started collecting the bits for this job...
     
  19. acotrel

    acotrel

    Joined:
    Jun 30, 2012
    Triumph pushrods are often made out of high-tensile steel tube instead of solid aluminium and are much thinner than Norton pushrods.
     

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