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minor detail question - carburator manifolds

Discussion in 'Norton Commando Motorcycles (Classic)' started by joe czech, Sep 12, 2019.

  1. joe czech

    joe czech

    Joined:
    Feb 21, 2019
    this maybe a dumb question, but what is the correct (factory) finish on the two carburetor manifolds? I would think, natural aluminum, or aluminum alloy. for some reason, mine are painted silver. I can't trust or second guess anything on my 74 Mk2 - damn near have to question everything - :D
     
  2. HRD

    HRD

    Joined:
    Mar 21, 2011
    That was standard on my then new 850Mk2a 1974 .
     
  3. joe czech

    joe czech

    Joined:
    Feb 21, 2019
    ??? - what was standard - natural or painted?
     
  4. baz

    baz VIP MEMBER

    Joined:
    May 26, 2010
    I think my manifolds were painted silver on my mk2a
     
  5. wirespokes

    wirespokes

    Joined:
    Jul 16, 2019
    From his answer I took it to mean painted silver was stock. Let's see if I'm wrong. :)
     
  6. blaisestation

    blaisestation

    Joined:
    Apr 10, 2008
    June 74, silver painted inlet manifolds
     
  7. Time Warp

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

    Joined:
    Dec 3, 2012
    Dec73 Mk2a, no silver paint including the engine cases which I believe I was the first to spilt.
     
  8. lazyeye6

    lazyeye6

    Joined:
    Feb 28, 2014
    My manifolds were unpainted alloy, but who knows what happened before I got them. My engine cases were painted, as I believe it
    was the factory practice to seal up the very porous sand cast cases so as to not leak oil.
     
  9. joe czech

    joe czech

    Joined:
    Feb 21, 2019
    mine appear to be sprayed - not brushed. IF a previous owner painted my original manifolds, they did an outstanding job - they were very neat and very anal about their workmanship. definitely a factory like finish quality. I do find it odd that the factory would paint these pieces whereas the carbs and cylinder head are a natural finish. right now, and after reading some of the above, especially from Mk2a owners, i'm leaning toward the silver paint from the factory. one thing for sure, they were painted after the carb mounting studs were installed. I cleaned up my originals with simple green and a small nylon brush. they came out very nice and in a ready to install condition. looks like i'll leave things as is, unless someone can prove otherwise. thanks for the feedback - :)

    edit note - second guessing here - one thing, these manifolds appear not to be aluminum or a high aluminum content alloy - casting are too heavy. just guessing, but they may be a zinc-aluminum alloy (there are basically 3 different alloy percentages used in manufacturing. what percentage are these, I have no idea, and I could be totally wrong on the alloy thing). the silver paint may be strictly a cosmetic thing due to the nature of the casting material used. side note - the silver color appears to be the same silver used on the U/L fork yokes - o_O
     
    Last edited: Sep 13, 2019
  10. maylar

    maylar VIP MEMBER

    Joined:
    May 13, 2007
    Natural aluminum on mine - now they're chromed.
     
  11. kommando

    kommando

    Joined:
    May 7, 2005
    Nov 73 MK2a, painted cases but nothing on the manifolds.
     
  12. joe czech

    joe czech

    Joined:
    Feb 21, 2019
    follow up question - the factory lock washers used - are they internal tooth, or split lock washers? I see McMaster-Carr has smaller O.D. splits for cap screws. I did find smaller diameter splits in the parts box, but only three of the four needed. not even sure they're the ones for the manifold cap screws - just trying to put the puzzle together. the parts book and Old Britts exploded view diagrams shows what appears to be tooth lock washers. also, I have replacement stainless cap screws. were the originals black oxide caps? again, three in the box and four needed....
     
  13. maylar

    maylar VIP MEMBER

    Joined:
    May 13, 2007
    The exploded view of manifold washers shows what sure looks to be internal tooth locks -

    upload_2019-9-13_9-1-38.png

    ... But the description shows a plain washer -

    upload_2019-9-13_9-2-43.png

    It's been a while since I've had mine apart, but I believe they're star washers. My screws are black.
     
  14. joe czech

    joe czech

    Joined:
    Feb 21, 2019
    thanks Dave -- the old brits part number is the same, and is called out only as a 5/16 washer.
     
  15. acotrel

    acotrel

    Joined:
    Jun 30, 2012
    Silver paint on inlet manifolds is probably there to cure porous castings.
     
  16. C317414

    C317414

    Joined:
    Dec 17, 2017
    September 73 build date - unpainted aluminum manifolds and cases. I am the second owner and bought the bike with 1,100 miles on it 40 years ago. It was completely stock and unmolested.
     

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