Thread size

[seaducerpete]

Need to run a tap through my cmb turbo head so what size tap would I use?

 

[Mike Cathey]

Common glow plug threads are 1/4-32

 

[Daniel's Racing]

Need to run a tap through my cmb turbo head so what size tap would I use?

Turbo thread is metric 8mm X .75mm

 

[John Beardslee]

Pete,
If you have an old burned out turbo plug, you can make thread cleaner out of it. Pull the wire out and clean the face so no pieces of wire can come off. Now, using a Dremel cut off wheel cut grooves in threads to make it look like a tap. I’d use 3 grooves for a turbo plug. The grooves don’t need to be any deeper than the the thread groove and they only need to bet the width of the wheel.
John

 

[John Beardslee]

Pete,
As a general rule, it’s not recommended to use a tap to clean up threads as it will usually remove/cut material weakening the threads.
John

 

[Daniel's Racing]

Pete,
As a general rule, it’s not recommended to use a tap to clean up threads as it will usually remove/cut material weakening the threads.
John

Very true. The sharp edges of new tap will take away good metal and the fit will not be the same.

EDIT,
I did not read where this had been already posted.

+1

Cut some slots in the threads of a spent glow plug and debur it with wire wheel and it should clean up aluminum threads to factory specs if there is offending metal/debris the slots will remove it without oversizing the threads entirely.

 

[Mike Cathey]

I have found that it always is worth checking on a new glow plug that the wire doesn't extend past the bottom of the plug so that it doesn't bugger up the head button threads. If it's over long a few gentle touches at a 45-degree angle with a fine flat file takes care of it.

 

[rhomodel]

Ultrasonic bath will clean it very well.

 

[IntlAdmin]

I have to say it.... The thread title always has me looking at it just to make sure there are not posting issues. Then I see it is threads on a screw.