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Thread: Knuckle head gaskets

  1. #11
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    Quote Originally Posted by Chris Haynes View Post
    The MoCo always used copper head gaskets until the war time restrictions on copper during WWII came into effect. It was at that time that they started using asbestos gaskets. Copper gaskets can be annealed and reused. A thin later of aluminum spray paint makes a great sealer.
    Chris - When I saw your mention of annealing a copper head gasket I did a browser search on the keyword "anneal copper head gasket." One item that turned up I think is interesting in that this Brit bike enthusiast had even new copper head gaskets that were somewhat hardened and he recommended even annealing new copper head gaskets. I for one would like to hear how others react to his observations and comments. Here is the link https://www.classicbritishspares.com...ys-anneal-them

    Mike Love

  2. #12
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    Quote Originally Posted by T. Cotten View Post
    That's great info, Chris!

    But why should they need a sealer?

    Insulation?

    Why didn't they go back, when it was surplus?
    Just wondering, since they obviously went to ordinance brass for manifolds and stuff.

    ....Cotten
    PS: I couldn't get some 'corrugated' (probably Eversure) coppers to seal, with paint of course,... cold. Never fired.
    Tom: One reason I have heard for using the spray lacquer with suspended aluminum dust in it is that the aluminum fills in and helps seal any irregularities between the head gasket and the head. A friend of mine who had been a H-D master mechanic for 30 some years swears by it to give that extra sealing edge. Of course the use of a soft metal like copper and torquing was also probably to account for the irregularities in cast iron. It would be interesting to know if H-D ever had a service bulletin to recommend this procedure.

    Mike Love

  3. #13
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    It sure didn't help the 'corrugated' gaskets at all, Mike!

    Paint's good for composite gaskets, as it makes them much easier to clean off next time.

    ...Cotten
    PS: Irregularities like tool mark are good. They hold the gasket.
    Irregularities like the common warpage of flatties over the intake port are more than I would like to trust to a band-aid.

    Oh yeah, aluminum OHVs suffer from that too!
    Knucks not so much.

    PPS! Heat-Paint upon vintage productions of asbestos or cardboard-like head gaskets should be worth the gamble.
    Please do NOT use it upon modern adhesive-impregnated gaskets such as from my preferred supplier, JAMES.

    That means manifold gaskets, too.
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    Last edited by T. Cotten; 11-16-2019 at 04:41 PM.
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  4. #14
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    From Chris:The MoCo always used copper head gaskets until the war time restrictions on copper during WWII came into effect. It was at that time that they started using asbestos gaskets. Copper gaskets can be annealed and reused. A thin later of aluminum spray paint makes a great sealer.
    The 1940 parts books show11-36,cylinder head gasket for cast iron head 45" 1936-1940
    11-39 for 1939 WLDD & 1940 WLD, aluminum heads
    The asbestos/composite gasket was for aluminum head 45" models, starting with the first 45" aluminum head models
    11-39 does not appear in the '39 book so maybe problems appeared in '39 so they made the asbestos then
    No mention of different gaskets for ULH UH models
    Last edited by duffeycycles; 11-17-2019 at 11:09 AM.

  5. #15
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    Copper for cast-iron, Folks,..

    And composite for aluminum for all marques was the way I was raised.
    (Too many mentors to remember.)

    So that explains my original question, as we are talking Knuckles.
    Were OEM iron-head Sportsters' copper?
    (Gotta ask, because they were all trashed long before they reached my benches.)

    ....Cotten
    PS: I preferred composite no matter what. Cost, sealability, and insulation seems to make most sense.
    Last edited by T. Cotten; 11-17-2019 at 11:51 AM.
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  6. #16
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    Copper for aluminum causes issues on some 45" because of narrow area near the motor mount.
    K-models had no gasket?
    Sporty was copper..I think
    Last edited by duffeycycles; 11-17-2019 at 12:35 PM.

  7. #17
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    Quote Originally Posted by duffeycycles View Post
    Copper for aluminum
    K-models had no gasket?
    Sporty was copper..I think
    Copper for aluminum, Duffey?

    My autopsies showed they "imprinted" into the head,
    Whether beaten into them by a million million compression strokes,
    or by dielectric something or other.

    Good point about the aluminum Ks using just paint.
    After all, if you need it to seal copper, why bother with the copper?

    Conductivity?

    ....Cotten
    Last edited by T. Cotten; 11-17-2019 at 12:34 PM.
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  8. #18
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    Sorry Cotton,I did not finish the sentence..edited
    I use the asbestos on aluminum
    I have seen the imprint in aluminum as well

  9. #19
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    Quote Originally Posted by duffeycycles View Post
    Sorry Cotton,I did not finish the sentence..edited
    I use the asbestos on aluminum
    I have seen the imprint in aluminum as well
    Be careful, Duffey!

    You'll get an edit addiction like mine.

    Another arm-chair-engineer'd reason for the erosion:
    Aluminum and cast iron have very much different thermal expansion coefficients.
    Hard copper between becomes 'cutting edge'.

    ....Cotten
    PS: Just another reason why Knucks were the pinnacle of classic American motorcycle design.
    Last edited by T. Cotten; 11-17-2019 at 01:57 PM.
    AMCA #776
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