Petcock size

[taz]

Does anyone know what size and thread the fuel petcock on a 1972 Wombat is ? Please and Thank You...

[hodakamax]

Hey Taz, go to the "Search" on the upper right of the page and type in "petcock". The answer is hiding there.

Max

[michael_perrett]

It is a 1/8" British Parallel Pipe threads.

Mike

[taz]

OK took my old petcock in to town and fitted it up perfectly with 1/8th IP ( iron pipe )

[michael_perrett]

The US pipe tap is, I believe 27 threads per inch, while the British is 28. Close enough

Mike

[bchappy]

I think you are right Mike as I picked up some 1/8" IP plugs to use while cleaning out a 72 Combat Wombat tank and they screwed in about half the way and then got tight.

[Zyx]

British parallel threads are not tapered. U.S. Iron pipe threads, such as National Pipe Thread or NPT, are tapered. In other words, the two are a mismatch no matter how you look at it. The question will be how you intend to use the parts, what they are respectively made of, and how much leakage is to be tolerated. I would expect threading brass British Parallel into an iron NPT female will distort the brass threads if you tighten them. Up to you.

What are you trying to fix?

[michael_perrett]

If you want to run 1/8 tapered pipe threads in the Hodaka tank, just taper with a US 1/8 tap.

[bchappy]

But if you rethread the tank the standard petcocks will be off by one thread. Correct?

[michael_perrett]

If you are referring to Hodaka petcocks as "standard", yes. My reason to use the tap is for a different installation, although not necessary as proven by experience.

Mike

[RichardMott]

I had to chime in here. Why would you change the set up from BPT to NPT? The petcocks are available. They use a gasket. Seems as if one is unnecessarily changing the design. I have been belittled on this site for not using metric hardware. Where is Ed? He usually has something to say in these matters.....