| if you need to install thread inserts, turn that cylinder to top dead center with the valves closed, insert a rag into the spark plug hole to help keep aluminum chips out of the chamber and use grease on the tap, be very careful to retain the tab if you use a helicoil kit and not let it fall into the chamber, then blow out the cylinder after pulling the rag out. i have done this successfully to a couple of heads, use locktite on the helicoil insert when installing it and antiseaze on the plug and you shouldn't have any problem with the new threads unscrewing when it comes time to replace the plugs again.
Murphy was an optimist |