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Norris Cam and Regrind Questions

Discussion in 'Norton Commando Motorcycles (Classic)' started by swooshdave, Sep 10, 2019.

  1. swooshdave

    swooshdave

    Joined:
    Apr 15, 2009
    A friend of mine pulled apart his engine (850) and found the cam to be pitted. So he bought a core cam and had it reground.

    When he brought the reground cam over I thought it looked strange. It was apparently reground to Megacycle specs(?). I'll try to post the specs soon. The lobes are very steep.

    I helped him get the crankshaft pinion off (thanks @Mike T!) so he could split the cases and get the pitted cam out. Then he noticed the pitted cam was marked Norris SS.

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    So what would you do? I don't know if you can tell how pointy the lobes are in these pictures.

    It was done by a local company that I suspect is use to doing cars cams and perhaps big four cylinder motorcycle cams. Not sure how familiar they are with Nortons.

    Reground cam looks odd. Norris cam is pitted.
     
  2. Time Warp

    Time Warp .......back to the 70's. VIP MEMBER

    Joined:
    Dec 3, 2012
    It must be the picture, that reground lobe looks like an insane lift speed with a ski jump closure along with minimal duration.
    Does it even have a transition over the nose.
     
  3. johnm

    johnm VIP MEMBER

    Joined:
    Feb 26, 2008
    Your best bet is to rough assemble it in a set of cases. Put on the barrel with the followers. Mount a degree disc on the end of the cam where the sprocket normally fits . Put a pushrod on the follower and then record the lift profile with a dial gauge vs degrees. Remember you usually put the degree disc on the crank. Then compare the profile to those on Dynodave’s site.
     
  4. gortnipper

    gortnipper VIP MEMBER

    Joined:
    Nov 11, 2013
    Norris SS is Megacycle 560-NSS now.
    Screenshot_20190911-193813_Drive.jpg

    Edit: corrected typo on MC #
     
    Last edited: Sep 11, 2019
  5. dynodave

    dynodave

    Joined:
    May 28, 2003
    GN Read the chart you provided...
    5600-SS is the 2S combat grind

    The Megacycle (norris SS) .359" in/ex is a bit hotter than a 5600-NR but not as hot as a PW3. I have not had access or tested/profiled a similar symetrical cam.

    SD The regrind reduces the base circle and may require a new set of push rods...did they re-case harden the cam? I would not use your cams on a bet...maybe a web- hard face weld regrind to a symetrical NSS .359 lift on a full diameter core.
    Just get a new NSS cam from megacycle?
     
  6. swooshdave

    swooshdave

    Joined:
    Apr 15, 2009
    Here’s what the shop said they reground it to:

    [​IMG]

    [​IMG]

    I can’t imagine that profile would be kind to a flat lifter.
     
  7. Madnorton

    Madnorton

    Joined:
    Jun 9, 2008
    Can't imagine that profile would be kind to any lifter!
     
  8. swooshdave

    swooshdave

    Joined:
    Apr 15, 2009
    Does anyone have a good used cam for my friend? New cams are not cheap.

    Although the ones from Andover aren’t bad, under $250. Unfortunately not in stock.
     
  9. o0norton0o

    o0norton0o VIP MEMBER

    Joined:
    Apr 27, 2015
  10. Hortons Norton

    Hortons Norton

    Joined:
    Oct 12, 2007
    Not that I know much but why is the bearing surface so small? It is a nasty profile.
     
  11. swooshdave

    swooshdave

    Joined:
    Apr 15, 2009
    Do you mean on the primary end of the cam?
     
  12. jseng1

    jseng1

    Joined:
    Nov 26, 2009
    That cam is just wrong. Way too sharp on the nose. Someone miscalculated.
     
  13. Robert_Norton

    Robert_Norton

    Joined:
    Dec 21, 2008
    .


    I have a few cams laying around, but I'm not entirely sure what they are. I think I have a clean stock cam with the matching lifters somewhere. Feel free to have your friend contact me directly. I'm in Seattle at four, two, five, four, eight, six, six, zero, four, zero


    First I'd work with the cam grinder, though. If they're at fault I think it would be unusual if they won't guarantee their work.




    .
     
  14. gortnipper

    gortnipper VIP MEMBER

    Joined:
    Nov 11, 2013
    Sorry, typo. That should have been 560-NSS.
     
  15. swooshdave

    swooshdave

    Joined:
    Apr 15, 2009
    Sweet!
     
  16. Hortons Norton

    Hortons Norton

    Joined:
    Oct 12, 2007
    Yes. Is the MK III shorter?
     
  17. illf8ed

    illf8ed

    Joined:
    Dec 30, 2003
    Hi Dave
    I have a Norris RX. The open and close on the spec you show are very narrow compared to the RX sheet from Norris.
    RX intake open 54 BTDC close 82 ABDC
    Exhaust open 82 BBDC close 54 ATDC
    Overlap 108 degrees
    Lift at the valve intake .424 with tappet clearance .006
    Exhaust .425 with tappet clearance .008
    Physically the cam lobes on mine are much fatter.
     
  18. swooshdave

    swooshdave

    Joined:
    Apr 15, 2009
    It would be interesting to see where they got their specs from.
     
  19. swooshdave

    swooshdave

    Joined:
    Apr 15, 2009
    Am I correct in assuming you don’t want to run a 2S in a stock 850?
     
  20. WZ507

    WZ507 VIP MEMBER

    Joined:
    Dec 26, 2013
    Many people do.
     

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