Spark plug thread repair

[Tony Hart]

I am rebuilding an engine and bought a new top end, not cheap. I put the plug in to do a leak-down test and it literally dropped in. There is about half a turn of thread at the bottom of the plug hole. This will have been about the third time I fitted a plug in the head. Don't think I had overtightened the plug. When I took the head off (again) there is no depth to the threads and no sign of stripped aluminium in the barrel. All by the by but my question is; can you reliably repair this thread with a kit without being forever paranoid about it failing?

The head is a unique design, (as far as I'm aware), and I don't fancy paying £100 for a new one if I can help it

Cheers

Tony

[MickYork]

Plenty of repair kits on ebay with various lengths of inserts. Done correctly and loctited in I don't see a problem

[Warkton Tornado No.1]

I bought a HeliCoil Sav-A-Thread M14 x 1.25 Spark Plug Repair Kit years ago ‘just in case’ when I saw one @ the right price (cheap!)

Eventually, it was needed & worked really well. I would totally recommend them & I have no doubt that the resultant repair is far stronger than the original.

[dickie]

I bought a HeliCoil Sav-A-Thread M14 x 1.25 Spark Plug Repair Kit years ago ‘just in case’ when I saw one @ the right price (cheap!)

Eventually, it was needed & worked really well. I would totally recommend them & I have no doubt that the resultant repair is far stronger than the original.

Agree. I stripped a thread when replacing a plug in a ham-fisted manner on a p200e years ago. Nearby garage fitted a helicoil and it lasted years. Until a scrote stole it in 1986; maybe he's still using it. Rob, any news on my helicoil?

[Tony Hart]

Many thanks all. Just ordered one so will see how I get on.

Tony