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Thread: Manifold Counterweight

  1. #1
    Join Date
    Apr 2009
    Location
    New Mexico
    Posts
    153

    Default Manifold Counterweight

    Just wondering how imperative having the counterweight is for the earlier manifolds with the heat flap? I just put an NOS manifold on that has the flap inside, and I can get everything for the whole counterweight setup, but I was wondering how important it actually is? Obviously it could get funky in the summer if the flap is only directing the exhaust up to the intake manifold, but Is there a way I could just make sure it's only diverting the exhaust down? So I wouldn't have to worry about the flap sticking open or closed if the bi metallic spring fails?
    Thanks.
    1956 86" S1
    1957 88" S1
    1967 109" SIIA NADA

  2. #2

    Default

    As you know, as the exhaust gasses heat the bimetallic spring, it expands and unwinds. The weight works in tandem with that spring and helps pull the valve steadily open and hold it open as the spring heats and unwinds. Without the weight, it would take much longer to open, and it may not open at all (the spring could simply uncoil, expanding outward without putting any pressure on the valve to turn)! The weight definitely has a job to do, not only in effecting the timing and duration of holding the diverter valve open, but as you acknowledge, it also serves as a "fail-safe" in case the spring breaks, where it's mass will continually hold the valve open regardless of engine or ambient temps.

    Rebuild it as the engineers designed it and enjoy its simple, trouble-free operation (a bit of preventive spray-lube maintenance will help!), or you could wire it open if you don't live in a climate where your carburetor ices up regularly.

  3. #3
    Join Date
    Apr 2009
    Location
    New Mexico
    Posts
    153

    Default

    Thanks for the input.. I generally don't drive it when it's below 20F because they use copious amounts of salt on the roads around here, so I haven't really ever had an icing issue. I guess I'll wire it open for now, so it just diverts the gasses down, and slowly accumulate all the parts for the counterweight (spring, weight, etc...) in case I do end up having icing problems.
    Thanks again
    1956 86" S1
    1957 88" S1
    1967 109" SIIA NADA

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