Re: stripped spark plug thread

[rudderless]

I have fixed several old snowmobile motors using a 3/8npt steel nipple. I tapped the inside of the 6" nipple on one end. I cut off the thread on the nipple off the same length as the head is thick. Used a sharp pipe tap to cut new tapered threads in head, use oil . Stop tapping when the nipple is one thread short of threading fully in by hand. Degrease both parts. Thread on an old plug, no washer on to repair insert. Use locktite or even 518 sealer on insert. It should make up in one turn tight with a wrench on the plug.

If the motor overheats bad the insert might come loose but can be resealed after the event.