Stripped spark plug thread - Sprint

[gmsclassics]

When I put this engine together a few years ago, I now remember using a head which had one of the spark plug threads that was a little weak, but had cleaned up okay. That decision has now come back to bite me with the spark plug now going round and round, refusing to come out. With the taper seat, the question is - is it possible to helicoil the thread in situ or do I have to remove the head and re-threat from the inside out? I suspect the answer is the latter but I am ever hopeful....

Geoff

[tony g]

You can do it with head on. Lots of grease around drill and tap to catch as much as you can. Make sure the helicoil once fitted is below the tapered portion before knocking the tang off. Use an air line to blow out the tang and any debris, but the tang must come out as its hard,

Tony

[80Sprint]

Unlikely to stop all the debris going in to the cylinder so I would personally pull the head off.

[soe8m]

Unlikely to stop all the debris going in to the cylinder so I would personally pull the head off.

Alloy debris in the cilinder from drilling etc does not harm in any way. It's gone in seconds.

Jeroen