Desmog Tube Removal

[Valk_ca]

Just took the initiation ride. Went about 25 miles and the frost plug on cylinder #1 blew. Had added JB Weld to it after pounding it in. Must not have pounded it in deep enough. Is there a way to know when you've pounded the frost plug far enough? Should it bottom out?

I read on another thread somewhere that you can screw an allen screw into the frost plug after you've pounded it in. Anyone know what size allen bolt it would be?