ORIGINAL: Kevin Y
actually JB Weld probably will not hold up. JB weld is not designed for the temperatures that a gas engine will produce. It will work for a little while but overtime it will become brittle and crack off. I would look into one of the Locktites that is designed for high temps. I know that there is a version of the green locktite that works well and is actually used on the case of the DA engines.
Likely the DA engine case does not get near to the 450 degree temp talked about here. That does not mean that it will not work with the adapter insert in the head, just maybe more research needs be done. TOM has had a lot of experience in this area.
But, may a muffler cement that contains silica might work at these high temps. I have bonded a lot of car muffler tailpipe/header joints with the stuff and the metal rusts away before the cement lets go. I would not let any of the silica cement get into my cylinder!!
Sincerely, Richard