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Late 1972 Engine Rebuild - Cam Bushings?

Discussion in 'Norton Commando Motorcycles (Classic)' started by northern750, Jan 12, 2020.

  1. northern750

    northern750

    Joined:
    Jun 18, 2009
    I noticed when I took things apart that I have a non-scrolled cam and non-scrolled cam bushings in my engine cases. Some research on this forum revealed that this is a bad combination. Near 40K miles, cam and bushings are in very good condition and there was a nice film of oil on the parts at disassembly. I also noticed the cam washer had no tang on it - I was worried that this had broken off but maybe the cam washer was installed with the tang removed?

    I was hoping to avoid the expense of a new camshaft but it looks as though I will need to fit one with scrolling.

    Has anyone else opened up an old set of cases to find neither bushings or cam were scrolled with no apparent problems?

    Thanks.
     
  2. Torontonian

    Torontonian

    Joined:
    Dec 28, 2009
    Who owned it before you ? I'd be calling up to ask , hopefully they knew of the need to remove any tang on that washer. If not then that little bronze piece could be sitting in bottom end oil . If you can't contact the P.O. then carefully look for it. On my Combat I removed the tang , the cam ends and bushings were scrolled to mate with solid unscrolled.
     
  3. kommando

    kommando

    Joined:
    May 7, 2005
    Just get someone to machine scrolls on your current cam journals.
     
    dynodave likes this.
  4. comnoz

    comnoz VIP MEMBER

    Joined:
    Dec 10, 2008
    I can scroll your cam.
     
    dynodave likes this.
  5. northern750

    northern750

    Joined:
    Jun 18, 2009
    I know the last three owners of the bike, from early 90s to when I bought it ten years ago - none had had the engine apart and from the look of things when I took the cases apart, I don't think they were ever opened up - there were no marks on any of the fasteners and the crusty case sealant had been on there for decades.

    This may be the excuse I need to put a new cam and followers in.

    I couldn't find the camshaft washer tang, it was either removed on assembly of the engine or got sucked through the oil pump although it's not damaged.

    Should I remove the tang on the washer when I reassemble the engine? Is this just to avoid it breaking off in use or is there another reason to remove it?

    Thanks.
     
  6. concours

    concours VIP MEMBER

    Joined:
    Dec 29, 2011
    Be sure you learn all about the current crop of available cams & lifters before you bin yours.
    It may make you reconsider.
     
  7. illf8ed

    illf8ed VIP MEMBER

    Joined:
    Dec 30, 2003
    Had the same problem when I put a double S cam back into my ‘72. I don’t remember who, but someone on this site scrolled my double S combat camshaft.
     
  8. cjandme

    cjandme

    Joined:
    Feb 5, 2011
    I would take or send your cam to Mr. Comstock of the Norton machine shop dot com if you intend to re-use everything else on your rebuild, it would be the most cost effective. If you wanted to upgrade your bike with what is available nowadays I'd go with JSmotorsports new stuff.
     
  9. comnoz

    comnoz VIP MEMBER

    Joined:
    Dec 10, 2008
    The tang on the washer was most likely removed at some time. The other possibility would be it is stuck in the passage between the pickup hole and the pump. If it got to the pump the pump would be destroyed -no two ways about it.

    If you replace the washer then cut the tang off the new one.

    You will also need to do the oil pump pickup mod. ie plug the pickup hole at the front of the engine case and create a new hole near the back of the case. Otherwise you will have too much oil in the cases at highway speeds and you will have leak problems.
     
    Last edited: Jan 13, 2020
  10. Torontonian

    Torontonian

    Joined:
    Dec 28, 2009
    The stoopid locator washer tang for the Combat series was a bad idea. It was to prevent the washer from spinning freely with the cam. The factory bloke took pliers and bent the tang locator stub which went into a drilled hole in the timing side casing for it with pliers , it cracked halfway when he did that. Miles later it would maybe (or not if lucky) break off what-with the rattlings and all. You can just bust off the cracked tang with the same or modern pliers and rock n' roll to heaven. If it's already missing and you know the bottom end has not been apart by P.O.'s then you have to search for it. Bronzy-brass colour tiny dangerous P.O.S.
     
  11. northern750

    northern750

    Joined:
    Jun 18, 2009
    Well, it looks like the tang was cut off since it's not in the oil passage and the oil pump seems okay.

    I'll be doing the rear case oil intake mod, 'Dynodave' style, and I'll add a CNW breather.
     
  12. dynodave

    dynodave

    Joined:
    May 28, 2003
    IMHO I would never use the 06-2600/01 bearing system in a 200000 series engine.
    Break off the tab and the thrust washer could EITHER stand still and absorb the thrust caused by tach drive OR tabless 2601 rotates and use the aluminum case as the wear surface.
    Sorry not in a motor I would put together...
     
  13. johntickle

    johntickle

    Joined:
    Dec 3, 2009
    If you have a thrust washer then you also have the non-flanged "scrolled" bushes (they have an "X" shape groove at the top). If it ain't broken don't fix it.
     
  14. northern750

    northern750

    Joined:
    Jun 18, 2009
    No scrolling in the bushings on my bike, smooth cam and bushings...
     
  15. northern750

    northern750

    Joined:
    Jun 18, 2009
    What's the alternative?
     
  16. dynodave

    dynodave

    Joined:
    May 28, 2003
    all early NHT up to 20M3S are thick bush
    From 200000 to end of commando are thin bush
    a pair of 75 MKIII bushes or even better one 73-74 850.
    both are smooth, you should scroll the cam journal
    All smooth journal cams are a throw back to a poorly advised engineering change and after recovery there were probably no more smooth journal cam being made.
     
    illf8ed likes this.
  17. pierodn

    pierodn

    Joined:
    Nov 10, 2012
    Found the same non scrolled bushs and 2S cam both in 1972 Combat.
    Engine seemed never opened before.
    The previous one owner confirmed it to me.
    I have then scrolled the cam.
    Ciao
    Piero
     

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