Oh, I didn't catch where you had said that this valve was in the tank side. I thought that it was the head pressure release valve on the cylinder head. Just go ahead and drill it out and let the chips fall in the tank. Filling and emptying the tank a few times should get rid of 90% of the chips and as long as you put some kind of filter on the outgoing line, it should catch any remaining debris that comes out of the tank. The minor diameter for a 1/4"NPT (which most of them are) is 7/16". If you can get a drill bit the next size under(27/64"), you should be able to use the hole as a pilot and not even have to mess up the existing threads. You may have to dig the remains out of the threads with a small pick.
Comment