I have done this one or two times in the past at work and seemed to work but been so long i forgot does a plug tap just clean up the threads or actually make hole bigger for helicoil i put my fuel pump and carb back on finally got it to run and it blew the plug right out of it the threads were messed up befopre i got it it just took one or two more times pullin plug for them to actually ruin are there any posts on this anyone can lead me to also 