Reply To: Stripped Spark Plug Hole?

[amuller]

Helicoil thread inserts work fine if properly installed. Sometimes they are used on new motors. I would take the head off. If you do it carefully you should be able to save the gasket. But if the head bolts don’t want to move, you can grease up the tap to catch chips and probably be OK.

But these heads should be easy to find. Disregard ripoff ebay prices. You can lap them flat if you have something that can serve as a surface plate. Piece of plate glass, or even a table saw table is likely good enough.

IMHO, contrary to a lot of official advice, it is often safer to tighten plugs by feel. Especially if using anti-seize that may have a low coefficient of friction. And torque wrenches have their own issues, such as the pointer hanging up so you keep on pulling. Of course, a new plug will have a new crush-type gasket and so the feel of the first tightening will be different.