need o2 tap size

[Dayton08]

I screwed up the inside threads of the bung for the 02 on my hpipe.

what size of tap do i need to re-tap it.

thx.

unless should i grind that bung up(or plug it).. and get a new one welded on?

 

[1970 slantroof]

I THINK most of them are 18 mm like the big tapered seat spark plugs. If you have one of the "clean up" taps for plug holes, that should work. I would compare the 18 mm tap to you O2 sensor to verify.
Howard