Hello, im afraid im back for more advice -
I have had my spark plug out many times without issue but today i went to remove it to check the state after a new carb test.
the plug seemed a bit stiffer coming out and when it was out the thread was no longer 14mm but 15.7mm - so im assuming i have removed a previous insert?
I can put the plug back in and out ok but cant remove the thread from the plug itself.
So, im guessing i dont need to re-cut a thread in the head as this is still ok, but i do need a new insert in there so i can change plugs if i need to, i also have a vape EI kit that i need to install but currently am not able to screw in a dial gauge either.
What is the easiest/cheapest way to get a new insert and make sure it stays put when the plug is removed?
The engine was very hot when i removed this plug so could that have caused it ?
Thanks
Steve
Has the spark plug hole been "helicoiled". It might be that the spark plug thread was previously "stripped" by over tightening and the damaged thread was repaired by inserting a helicoil.This is a standard procedure. It would seem your tapped thread helicoil has become attached to the spark plug. If that is so you could obtain and fit a new helicoil and use a new spark plug or you could attempt to remove the old helicoil (using pliers or similar gripping tool) and refit it.
The engine being hot might have loosened the grip of the helicoil on the cylinder head. It might be that if you had screwed it back in immediately and let it cool you might have just removed the spark plug alone.
In theory it is not impossible to just screw the "adapted" spark plug back in from whence it came and continue as before. But that is NOT an ideal situation. In other situations I would say "superglue" the coil back in. But it is quite possible that the cylinder head gets to over 185C - at which point the super glue melts.
I have no idea what high temperature fixing compounds exist to secure the helicoil. It is one reason many do not try to helicoil the spark plug hole.
If this is not a helicoil then I have no idea what the situation is. Good luck either way.
It does look like you have a plug thread insert and its come out on the plug. You need to get this off the plug and either back in the head or get a new one. The reason is that screwing the plug in with the insert will wear the head so the thread becomes too big to hold any insert. The insert may not cost much and find out if it needs to be high temp loctited in.