Do yourself a favor and use a 1/4" NPT tap to thread those holes, then use 1/4" NPT steel Allen plugs in them. Brass or aluminum will melt out eventually if any exhaust gas at all gets to them. Don't ask me how I know this!
Jerry
Wow, just how hot do the exhaust gases get?
That being the case, I'll just go with a steel plug. I would like to thread those holes and use a allen type plug, but I just dont have the proper tap to do the job.
