Petrol tap gauze filter thread

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Roderick.Bradley
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Petrol tap gauze filter thread

Post by Roderick.Bradley »

I have inherited a push-pull petrol tap and a gauze filter to fit to it but the filter has no thread in it at the moment to screw the filter into it & so I will have to tap the filter to take the filter
The thread on the filter is 1/4 x 40TPI as best I can measure. Is this 1/4 x 40TPI ME (Model Engineers) thread or something else altogether?

Rod
Les H
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Re: Petrol tap gauze filter thread

Post by Les H »

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Last edited by Les H on Sun Jul 24, 2022 9:36 am, edited 1 time in total.
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simon.holyfield
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Re: Petrol tap gauze filter thread

Post by simon.holyfield »

Can you show us a picture? Filters are usually soldered into the top of the tap...
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Re: Petrol tap gauze filter thread

Post by nevhunter »

The double tap with reserve has a soldered brass mesh filter. Some single taps have the fine 1/4" internal thread. I've sometimes fitter lawn mower nylon filters to them.( Screw in) satisfactorily. Nev
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Re: Petrol tap gauze filter thread

Post by Roderick.Bradley »

I have seen filters soldered into taps. I think soldering would a tricky business with gauze and such a small fixture and I am not sure how that would have been done originally. I think I would make a mess of it.

I think I have seen instances where the filter was screwed in & could be removed. I'd feel safer trying to tap a thread in the petrol tap recess & that's why I wanted to be sure what the thread was. (The thread on the petrol tap that screws into the petrol tank boss is 1/8 BSP, by the way).

The thread diameter on the brass/copper filter is 1/4" O.D. as best I can measure. The only 1/4" O.D. x 40 TPI thread I can find reference to is M.E. 1/4 x 40TPI.

Thanks for the lawn-mower filter tip, Nev.

I don't know how to up-load a photo, Simon.

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Re: Petrol tap gauze filter thread

Post by admin »

Roderick.Bradley wrote: Sun Jul 24, 2022 9:22 am I don't know how to up-load a photo...
Forum Help - Posting Images should be of assistance....
viewtopic.php?f=35&t=193

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Les H
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Re: Petrol tap gauze filter thread

Post by Les H »

Roderick.Bradley wrote: Sun Jul 24, 2022 9:22 am (The thread on the petrol tap that screws into the petrol tank boss is 1/8 BSP, by the way).

Cough, Cough, Mr Bradley...As said by me, the USUAL thread size on a petrol tap is 1/4 BSP
Petrol Tap Size.JPG
BSP SIZES.png
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Re: Petrol tap gauze filter thread

Post by Roderick.Bradley »

Yes, Les, you're right. 1/4 BSP is the usual petrol tank tap thread size. But for reasons in the past only to be guessed at, it's a 1/8 BSP in this instance. Not the best size.

I think I will go ahead with tapping the other (filter) end of this petrol tap to 1/4 x40 TPI M. E. to be able to screw in the filter.

Rod
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Re: Petrol tap gauze filter thread

Post by Roger Gwynn »

All Ariels, except the 2 strokes used, 3/8 BSP, yes 1/4 is more common on the more common sort of motor cycle but not on the better sort. That is the end into the tank, the outlet is usually 1/4 except on the post war Colts when it is push on and the 1954-58 SQ4 when it is 3/16 BSP, which is a bastard thread frequently misnamed 7/16 BSP because it measures 7/16 but as we all know that is not how pipe threads are named!
Roger Gwynn, Membership Secretary, curator of the Machine Register and the works drawings. Director of Draganfly Motorcycles, Craven Equipment and Supreme Motorcycles mostly retired.
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