Thread on Cox .049's

[Vince Mankowski]

Anyone know what thread is on the Cox .049 glow heads? I think it may be the same thread on the cylinder & the case that thread together (?).

It looks like 17/32-40...... but maybe 13.5mm x an unknown pitch......(?)

[Tim Wescott]

My notes say that it's 0.527 OD, 40 pitch.  But that's for a head that was done before I understood thread profiles as well as I do now, and I don't think I "really" understand thread profiles even yet.

It's a totally non-standard diameter for 40 pitch, so Cox could have made it to be whatever they wanted.  If you're going to cut the threads, just cut & try (and remember to flatten the tops -- that's part of what I didn't understand about thread profiles when I made my notes).

It is 40 TPI, as are the threads on the .09.