1/4"-32 tap

ian1954 wrote:That is the correct tap for a glow plug. 1/4 x 32 UNEF. Be careful though, that looks like a taper or 1st tap. It may produce a tight fit unless you run the full length.

I don't think it matches the 049/051 venturi though. There was a thread about this but I can't find it.

I believe I checked a TD venturi by screwing a standard glow plug into it.

For both taps and Dies for 1/4 x 32 don't forget the Harry Higley set. Harry Higley was recently bought by Sullivan.

George

Ah yes, Harry Higley. Thanks. Here it is:
http://www.ebay.com/itm/NEW-Harry-Higley-s-Glow-Plug-Tap-1-4-32-GPT014-NIB-/291224794222?pt=US_Hand_Tools&hash=item43ce59b46e

RknRusty wrote:Ah yes, Harry Higley. Thanks. Here it is:
http://www.ebay.com/itm/NEW-Harry-Higley-s-Glow-Plug-Tap-1-4-32-GPT014-NIB-/291224794222?pt=US_Hand_Tools&hash=item43ce59b46e

This tap looks much better for glow pug work

There are three styles of tap:-

The kind of hole to be tapped has much to do with the style of tap that’s best suited. Some holes go all the way through. Others, while not through holes, still are relatively deep. Some are quite shallow, little deeper than diameter. Each of these three kinds of holes through, deep-bottoming blind, and shallow bottoming, has a tap or group of taps best suited to requirements.

Taper Taps have 7 to 10 thread chamfers to distribute cutting action over many teeth and the taper also acts as a guide in starting.

Plug Taps (We in the UK call them second taps), with a chamfer over four threads, is most widely used in through holes and where there is sufficient room at the bottom in blind holes.

Bottoming Taps are made with just enough chamfer for starting in the hole, only 1 to 2 half threads. As the name implies, it is designed to thread blind holes to the bottom.

A taper tap, if you are using it for rethreading or cleaning threads, can cause problems - it is easy to get in "cross threaded" and ruin an existing thread. It is ideal for starting a new thread.

I usually use a taper tap (1st tap in the UK) and follow up with a plug tap.

For the venture tap I had 11/64 x 40 in my head. So I did some searching and found

https://www.coxengineforum.com/t5553-cox-killer-bee-backplate - this would indicate that the glow plug  thread would match.

Then I found this and realized the 11/64 x 40 was for a TD Pee Wee

https://www.coxengineforum.com/t3758-custom-pee-wee-020

Searching this site isn't easy!