Concentric float bowl plug.

[muskrat]

G'day Fellas.
I'm trying to work out the thread of the plug hole in a concentric float bowl. It looks like 9/16 x 26 tpi to me. Anyone know for sure?
I want to make fittings to check the fuel height. I had one before the fire
Cheers

[groily]

Just measured one on a couple of 626s and I agree with that Mr M.
I got 0.5615", for a nominal .5625. 26 tpi gauge looked perfick.
(About 10 thou too fat for 14 x 1mm, even if on a shortish length a 1mm thread gauge fits quite well too.)

[muskrat]

Thanks groily.
Just using verniers in the hole I got 0.520 then added twice the thread depth of 26tpi (aprox 0.020) = 0.560. Funny I used to have quite a few plugs.
Cheers