spark plug hole thread

cena

what is the best way to I could re-thread a spark plug hole. There is no thread left. Now this isn't for a car but for a chainsaw. I hope someone here can help

crubbeens

Hi, you'll have to helicoil the thread here's a youtube link explaining the procedure:http://www.youtube.com/watch?v=mHCv0xmeLHg

You will probably source a helicoil kit from ebay.

cena

Would I need to use a bigger tap to rethread or could I use the same tap size again

crubbeens

You will have to make the hole larger, the helicoil insert is a formed wire insert which will then take up the size difference. A helicoil kit will come with a correctly sized drill, tap and insertion tool. In practice if the thread is totally stripped you can get a away with just running the tap through the hole.

cena

crubbeens wrote: »

You will have to make the hole larger, the helicoil insert is a formed wire insert which will then take up the size difference. A helicoil kit will come with a correctly sized drill, tap and insertion tool. In practice if the thread is totally stripped you can get a away with just running the tap through the hole.

The thread is totally gone

crubbeens

Yep, that's not a problem. The thread will stripped to the core diameter of the thread in the cylinder head, so when you use the helicoil tap, the insert will replace the original thread. This sounds far more complicated than it is:)

working fool

I've done it on a strimmer engine
Pretty straight forward job

Just a tip
If ur drilling or re-tapping do it with the engine upside down
It stops the filings falling into the chamber