That's the ragged edge of the piece of gasket I tore of a intake gasket for the pressure test block-off plate. You can se a similar torn edge for the other side. C'mon guys, give me more credit than that
No way I'm going to throw the chicken bones to see what kind of "glue" I'm going to use on the thread repair. I've got to much time, sweat, blood and $$ tied up in this motor to take a chance like that. After much research and without question, I'll use the BIG-SERT. It's used for failed threads that were repaired or that originally had a heli-coil or similar spiral-wound thread device. The OEMs use them as well as major shops. The TIME/BIG-SERTS carry more load the the heli-coils do and being totally enclosed repeated ins and outs are not a problem. They "lock in" to the hole better too.
Those are my intentions, but... I'm not ordering anything yet, not till I know what I'm up against. I'll yank the heads next Sunday (temperature permitting) for a Monday machine shop drop-off and also do a close thread inspect. I want to take a detailed look-see at a good hole along with the bad one. I also need to see what it's going to take to get the old helicoil out without boogerin' the side wall of the hole up too much. I don't really know at this time how much wall thickness I have either.
http://www.timesert.com/html/bigsert.html