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Thread: Carburetor Lowspeed needle seat repair?

  1. #1
    Join Date
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    Default Carburetor Lowspeed needle seat repair?

    I hope I can ask another tech question here, Folks,..

    ...Without getting more crap thrown at me like my last question.

    GX Scheblers suffer from mis-aimed needles, like all Scheblers, even though they have brass thread inserts.
    Here (attached) is the best photo I can manage of a damaged seat deep within the 'well', resulting by the added insult of installing the wrong needle.

    The arrow points to a gouge in its rim; the dots in the middle of the hole are just point divots in the gallery from the wrong needle over-tightened, and not an issue. But not only is there a gouge, the hole has been enlarged by the overtightening of a fatter needle.

    Any ideas for a remedy that are actually practical?
    (Please remember that the threads in the body never point accurately at the hole, even though there is a brass insert.)

    Thanks in advance,

    ....Cotten
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    AMCA #776
    Dumpster Diver's Motto: Seek,... and Ye Shall Find!

  2. #2
    Join Date
    Jun 2001
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    Default

    Well, at least the raggers have been quiet, Folks!

    So if I cut a very thin, press-fit wafer of PEEK with a proper hole, gentle to the needle point, any ideas about how I can make it removable?
    Stabbing it with a tool risks damaging the existing seat further.

    Thanks again in advance,

    .....Cotten
    AMCA #776
    Dumpster Diver's Motto: Seek,... and Ye Shall Find!

  3. #3
    Join Date
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    Vancouver Island B.C.
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    Default

    With no experience with PEEK, and not seeing your picture clearly I can only surmise what your thoughts are. As for removal, what about applying heat with a heat gun to soften it then stick a very sharp dental pick in it and let it cool with the pick in it ( or maybe even put it in a freezer) until it's rigid enough to pull.

  4. #4
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    Dewey!

    PEEK's melting point is ~640 F, according to Wikipedia.
    That's why it works so well for manifold seals (when properly fit).

    The seat needs to be about three inches down in a ~.220" hole.
    The original drilling was undoubted piloted by the threaded insert, but after eighty years or more, the pressure of the detente ball against the needle knob skews it.
    (Potmetal Scheblers suffer even more.)

    I can make an indexable needle guide to correct the highspeed needle's aim, but only because the seat is visible.
    It seems impossible to observe the aim of a lowspeed needle.

    ....Cotten
    AMCA #776
    Dumpster Diver's Motto: Seek,... and Ye Shall Find!

  5. #5
    Join Date
    Jan 2005
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    Vancouver Island B.C.
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    Default

    Quote Originally Posted by T. Cotten View Post
    Dewey!

    PEEK's melting point is ~640 F, according to Wikipedia.
    That's why it works so well for manifold seals (when properly fit).

    The seat needs to be about three inches down in a ~.220" hole.
    The original drilling was undoubted piloted by the threaded insert, but after eighty years or more, the pressure of the detente ball against the needle knob skews it.
    (Potmetal Scheblers suffer even more.)

    I can make an indexable needle guide to correct the highspeed needle's aim, but only because the seat is visible.
    It seems impossible to observe the aim of a lowspeed needle.

    ....Cotten
    I wasn't thinking melting, just making it pliable enough to get something sharp into it.

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