timecert question, helicoil uncoiling Options

[VaccaRabite]

The skinny:
Spark plug helicoil is going bad - uncoiling out of the socket. I know that I want to timesert it to fix the problem.

BUT

Since the socket has a helicoil in it (that needs to come out) what size timecert do I need to get?

ALSO

How do I get the bad helicoil out of the head without doing further damage to the head? The head is off the engine, so I am not worried about bits of coil falling into the cylinder.

This site has MANY sert options, but I don't know which one I need. HELP?!
http://www.timesert.com/html/sparkplug.html

Thanks
Zach

[HAM Inc]

Thanks Dr. Evil. I'm happy to be of service! I've been reading your tranny rebuild tips lately very informative!
Zach you want the 15mm insert. If you pull the old wire out slowly with a twisting motion it will come out with minimal if any dmage to the threads.
Remember that the reason Zach needs a tap is to clean up the existing oversize threads and the tap then serves as a pilot for the counterbore operation. I suppose a plug style 16mm x 1.25 tap would work for the operation if the shank is the same size as the Time-Sert tool. But I'll bet a dollar the the Time-Sert tap will be easier to find and cheaper than a 16 x 1.25 plug tap.
For those of you on the West coast Pendergrass Tool is a Time-Sert rep in Somis, CA . Jim Pendergrass is a nice guy and has lots of specialized automotive tools. 800 926 1847
Another thing you need to watch when performing the countersink operation is make sure you don't go any deeper than it takes to just clean-up the surface that the compression washer seals against. If you go to deep the plug will sit deeper in the head and the first thread will be exposed in the chamber. It will carbon up and the next time you change your plugs it will unwind the insert, making a mess. If you use the 17mm insert the first couple of threads on the insert (the ones that swedge into the head) will protrude into the chamber and the swedge will not work. Been there done that!
Make sure you use Never-Seaze on your plugs! It doesn't take much to make a + difference. To much can cause ignition problems.