Topic: thread chaser for a D7EA plug

[hymodyne]

Hi all,

I've cross threaded a spark plug and need a source for a thread chaser for for the port.

any suggestions? The local auto parts store has nothing for such a small diameter plug.

hym

[Badboy]

I think that heli-coil makes heli-coils for that size,if it comes to that. However,I think you should be able to find a metric tap that would fit that. Some time ago ,we at the shop installed a heli-coil ,I believe in 10 mm. It was a standard metric thread,and I think you will find this is to. I have a plug that is the same size in my hand,it[the threads] measures 12x1 mm .You should be able to find a threadchaser,that would clean out your threads. MAC tools makes a rig in 14mm that goes down into the hole and then expands to back out. I have one and it works good if the first threads are messed up bad. But I do not know if it is made in 12mm. If your autoparts store don't want to get a  threadchaser,then they are pathetic. I do not know your skill level,but if you use a regular tap be very careful to get it started streight or you will bug up the theads even worse.I think the HeliCoil makes an insert that in 12mm,check with your autoparts store if they can get it.

[Lumbee]

...hey Hymo...how bad is it?  The least destructive option u might try is to make a "Po boy" chaser using an old spark plug...just take u'r Dremel and cut 2 or 3 grooves in it, and run it in/out of the plug hole a few times.  Next is to find a tap.  I had a plug hole that had minor damage and could not find a tap for it anywhere.  I think it was 12/1.25???  Any how what ever it was, nobody carried it...at least not the big boyz...sears/home depot/lowes.  So I used the above method with an old plug...the plug holes is still "sticky", but usable...

[Badboy]

Correction on the sparkplug thread. I just checked it with a thread gage and it is 12x1.25mm.  No matter ,you should be able to find a tap of that size. I The idea of making a spark plug into a thread chaser works to ,I have done it a few times.

[Jonesy]

Whatever route you take, make sure you grease up the chaser so no metal shavings will fall into the combustion chamber.