3/4" Oversize Bushing Installation Suggestions
This bushing has oil on it. It will need to be thoroughly cleaned before installing.
You shouldn't have to drill the blown hole to 21/32 for a 3/4 tap. Just tap it. The blown out hole usually ends up just about 21/32.
Tap the blown hole to 3/4-10. A tapered tap will start easier than a plug tap, but either will work.
Cover the tap in wheel bearing grease to stick as many metal chips as possible.
Use a 12-point socket on the head of the tap. You will not be able to use a tap handle.
After tapping the spark plug hole, unhook the ignition and crank the engine a few rounds to blow any chips that fell in the cylinder. Or, use a small adapter on a shop-vac.
Clean and dry the new threads, and the Bushing thoroughly. (w/ brake cleaner)
Screw your NEW spark plug into the adapter. ( the torque for this plug is 7-14 ft-lbs or 84-168 in-lbs )
Apply JB-Weld to the external adapter threads, (NOT the spark plug threads) and screw it into the hole and tighten with a spark plug socket.
Let the JB-weld cure for 24 hours before starting your engine.
NOTE: JB-Weld also has a quick-set formula which can cut the waiting time down to a few hours.
Good luck with your repair!