Is there anyone out there that knows the thread form of the thread of a standard glow plug? I know that the thread is a 1/4" x 32 tpi but what is the form (UNF, Whitworth...)

Without knowing the form I can't order a tap...

Thanks in anticipation.

Regards

That it's a Hanson, and a 1/4 32 NEF. Higley used to sell them. Hope that helps_bob

Bob's correct. I believe the "EF" stands for extra fine. You can find all this Info. in the "Machinery Handbook. Go to the local machine shop (or library maybe) and they should have a copy. Pat

For glow plug use either 1/4 x 32 NEF or
1/4 x 32 UNEF. Use 7/32 tap drill for 75%
thread.
Good Luck

Thanks to you all for replying. I now have a thread in my sticky mitts :-)

sorry, make that a tap in my sticky mitts...

When the threads are this fine they become very shallow in depth. Make sure your drilled hole is not at all oversize. Also make sure the tap is aligned with the hole for the entire tapping operation and a good TAPPING lubricant is used. Kerosene works well with aluminum if you don't have any commercial tap lube.

Good luck.

LF

Is that website back up yet? Miss that baby...