Glow Plug Thread

Can anyone confirm what the thread is on a standard glowplug? I measure a slightly oversize 6mm x 0.6 pitch or a slightly undersize 1/4" x 40tpi, but the thread is so short I can't be confident.

Before anyobne says google -there seems to be just as much confusion out there as here!

Thanks

Neil.

Edited By Stub Mandrel on 05/01/2013 20:10:46

Hi Neil,
The results from googling "model glow plug thread" seem to indicate the normal thread is 1/4" x 32 tpi This does not match your measured value of 0.6mm / 40 tpi.It looks like the plug you have is not standard.

Les.

Edited By Les Jones 1 on 05/01/2013 20:30:50

Its a UNEF 1/4x32 so 60degrees unlike out ME 1/4x32 which is 55deg

I got my taps from here when I built the Firefly, fitted perfectly on a standard OS plug

Edited By JasonB on 05/01/2013 20:37:25

According to wikapedia it is 1/4x32 UNEF .

Neil,

This seems to confirm Les' findings

MichaelG.

Jason beat me to it.

Edited By Michael Gilligan on 05/01/2013 20:40:00

Thanks for the rapid responses. I found wikipedia, but there seemed to be some disagreement. I eyeballed the pitch at 0.024" using a caliper (which is why I though 40tpi), but I reckon it is probably a standard one.

Not sure I've got 1/4" by 32 ME anyway, but I have a suitable threading tool - a homemade tap should be fine in the aluminium head.

Thanks again,

neil

From the ELFs book they can be 32, 40 and sometimes even 48 TPI