On this "new" rotary engine that i have, the oil pressure switch has been broken off. All that is left is the tread of the bolt. I have tried vice grips and no luck. Anyways, to fix this problem, do I have to drill out the remaining thread. Any suggestions.

 

You can buy a tool at the hardware store that drills into the bolt and grips then you can back the stud out.
I can't remeber what the heck you call them.
I would not suggest drilling it all the way out as you might get metal shavings in the block and that would not be good.

 

The tool is called an "easy out".

 

Thanks man