[mongocanfly]

I use the same...I've also done 3/8npt as well...
As far as what to do...remove the plug that's in the head...coating the drill and tap with grease will help with keeping shaving out of the head...I usually do mine on a engine stand where I can tilt it over..if I can do that I dont use grease on the drill..after drilling I use the shop vac to get the remnants outs..but I do grease the tap...