newracer previously posted:
"If the hole is deep enough to allow it I'd start with the standard tap, they are easier to start and get straight."
Seems to be standard procedure...start with the tapered tap, then go to a plug tap, then go to the final flat ended 'bottoming' tap. The biggest hassle is finding the taps, as heli-coils don't use standard tap sizes. Most heli-coil kits come with the appropriate tap for that particular size heli-coil - and most kits only have the tapered tap. The blind hole is about 1/2" deep for 1/4"x20 bolt thread.
Guess we are going to find out if I can get it to work - have to re-tap my oil pump mounting and the pump doesn't have the clearance to make the mounting holes bigger. I took the pump off as the gaskets have been leaking a lot of oil - think I found out why. One of the mounting bolts was completely useless and pulled out all the thread.