>>> My point was that "cleaning up" the threads on a conventional glowplug is going to lose rpm >>>

Oh my, they have medicine for people like that! ha, just kidding.

Not to worry, the die doesn't pull "substantial" material off of the rolled threads. The rolled threads are not that bad. It just takes a few imperfections or high spots off that would become the troublesome spots that could weld to the aluminum in the head under heat and pressure.

Thanks,

Ernie Misner