Fuel shut off

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white1j0
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Fuel shut off

#1

Post by white1j0 »

Is there supposed to be a gasket under the brass fitting that holds the gas shut off valve in place on the top of the tank, also the fitting on the cross over line is too small, I have '56 tanks and I think the cross over is for a '57 and later, not sure, does anyone know what size thread is on the top of the tank which the brass fitting tightens down on, I can only get about 1 1/4 turns, I'm going to have to chase the threads, Thanks Whitey
1950Panhead
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Re: Fuel shut off

#2

Post by 1950Panhead »

There is a round seal and a spring under threaded cap, 3/4-20.
Threads sometime rust or get crud, use wire brush or wire wheel on drill.
Jerry
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Re: Fuel shut off

#3

Post by RUBONE »

As 1950Panhead said, there is a spring and rubber washer, but also a steel flat washer. The rubber washer is convex on one side and is a packing washer. When the top cap is screwed down it compresses the spring which is sitting on top of the flat washer and in turn squashes the rubber washer creating a seal around the rod and also creating enough friction to hold it in the raised position. It should only be tightened enough to function correctly and not cranked down.
The crossover line threads are the same on all Panhead tanks, no difference in thread sizes. It is a common 1/4 inch compression fitting. Sometimes if removed with an open end wrench instead of a line wrench they will become egg shaped and not thread on correctly.
Robbie
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Re: Fuel shut off

#4

Post by white1j0 »

Thanks for the imfo. where can I find those washers at ???, Thanks Whitey
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Re: Fuel shut off

#5

Post by james »

olddude.com and CarlsCycleSupply
have everything you need.
Jim
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Re: Fuel shut off

#6

Post by Cotten »

I agree with Robbie, Folks,...

That the glandnut for the seal should not be "cranked down", as after all, it only has a knurl.
But in practice, it must be bottomed out firm; There is no real adjustability.

I believe the earlier seals were cork, and the spring was to continue to comress them through their brief life. "Rubber" seals improved things until modern fuels changed, and modern replacement seals probably changed as well.

As a pragmatist first, and a commercial purist (purista) second,
I have been using some neoprene roofing nail seals a roofer buddy gave me a decade or two ago.
A pair squeezes in perfectly with no washer or spring, and the putrid fuel swells them to a perfect grab upon the valve shaft.
I covet them jealously.

....Cotten
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