petcock / fuel tap operation

Discussion in 'Airheads' started by 70sbudget, Jun 17, 2019.

  1. 70sbudget

    70sbudget Adventurer

    Joined:
    Jun 12, 2019
    Oddometer:
    35
    Location:
    San diego
    is there a trick to getting these things to turn? on both sides i get a "clunk" when i try to rotate them. Do they get pulled out or pushed in before trying to rotate?

    1976 r90/6
    #1
  2. Disston

    Disston ShadeTreeExpert

    Joined:
    Aug 31, 2009
    Oddometer:
    15,321
    Location:
    Silver Spring, Md
    There's no pushing or pulling of the petcocks. Are they turning on and off? They normally sort of click on or off but the clicking feature is often lacking. If the handle rotates it may still provide gas.

    We do like for the peacocks to work because it is a safety feature to be able to turn the gas off when parked.

    If you have Karcoma they are rebuildable.
    #2
  3. 70sbudget

    70sbudget Adventurer

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    Jun 12, 2019
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    Yes they are the karcoma. I’m guessing they need a good rebuild and greasing after sitting for 30 years.
    #3
  4. Plaka

    Plaka Brevis illi vita est

    Joined:
    Jun 19, 2010
    Oddometer:
    6,394
    Location:
    Longmont, CO
    just rebuild them. very often new parts are not needed except maybe the plastic ring with the lettering on it. IIRC it just pops off. it may be omitted. i never liked them. remember one side is threaded to the tank with left hand threads.

    inside the aluminum handle flares out into a disc surface. i think ii has a hole. may have corrosion and pitting. must be smooth and shiny, as in polished. lap it out on a flat plate with increasingly fine sandpaper. the thickness does not matter. you can go deep into it if you need to but when assembled you want the working surface dead flat and normal to the body.

    there is a hard red fiber disk that bears on this surface with a spring behind ir proving pressure. the working surface may be scored. just flip it over and use the fresh side.

    screens come out and get cleaned. they are fragile.

    there may be a fiber washer (red) between the body and the tank. Some of there are integral with the screen. just leave it.

    It's fun to put back together because of that spring.

    clean up the sealing surface on the tank. i use a small whetstone.

    i mount it to the tank with Great White sealant on the fiber washer and nut threads.

    Do not use heat to take the body apart because of the fiber disk in side. Soak it if you have to. the wrench flats are under the black plastic ring with lettering.

    i do not use grease. the gas will just dissolve it quick. gas is the lubricant for the thing.

    if you find a lot of corrosion inspect the tank with care. 30 years does not do that, water does. so look for other damage.
    #4
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  5. 70sbudget

    70sbudget Adventurer

    Joined:
    Jun 12, 2019
    Oddometer:
    35
    Location:
    San diego
    Thank you for the beautiful detailed response!
    #5
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