[Rock Hornbuckle]

You will have bad luck with EZ-outs if you drill the hole too small, drill the hole as large as possible Use light pressure so as to not break the Ez-out. That is why I soak the drilled hole with PB Blaster, then not too much pressure on the EZ-out. If it doesn't break free at first, I then use a very small tip on my torch and apply heat in the drill hole, then use an eye dropper to shoot a quick spurt of ice water into the hole, then try the EZ-out again, repeat a couple times. If this fails, then I do the Heli-coil. I use an electro-mag drill to be able to center the bit in the broken stud. It's easier than pulling the engine to place it in a large press such as a Bridgeport. I have done this process on large industrial Steam Boilers usually located in the basement of buildings, where it's way too costly to disassemble and transport to a machine shop. I also have used the left-twist drill bits, and was able to cut the broken stud very close to the threads, allowing the old threads to be pealed out. You should be able to rent a Mag-drill.