I was trying to put a long awaited project back together the other night. Got it assembled and as I put the decomp in and started tightening it down.. it never tightened up. long story short the threads were 90% gone and I didn't notice it. So, I have this nicely machined cylinder. I can drill and tap to next biggest size and plug it with a custom made plug with a sealing washer or helicoil it but it is a larger saw and will be around the 200psi mark. I normally don't use decomps, but on larger high compression saws, it saves the recoils. I've never been a fan of helicoils in spark plugs, but there is only one size of decomps that I know of, so what are my options?
I don't have a tig, and don't want to try alum stick welding with the decomp hole in the chamber.. Figured that was my only other option
Yeah is there enough meat for a bigger size? You could go to a standard thread size if it's in between the next size metric.
I would helicoil it. They are commonly used in aluminum for threads that will see repeated use to prevent wearing out. A decomp that may never come out again or worst case very rarely will be fine.
There is a Helicoil product called Sav-a-thread. That could be your answer but you would need the sleeve for 10mm plug thread. (10x1.0?) I've done it for 14mm plug threads lots of times, but never seen it in 10mm. http://firewoodhoardersclub.com/forums/threads/sav-a-thread-spark-plug-hole-repair.3207/ I second haveissues advice, just heli-coil it. It's not likely you will need to pull the decomp multiple times.
