The problem with the helicoil is it will not transfer heat like a alloy time cert. If you helicoil it will burn it out of the head. I have done hundreds maybe thousands of spark plug inserts in many vehicles over the years. I have repaired many steel inserts in aluminum heads that have burned out, especially in ford modular engines. If timesert makes an insert that will work just be careful to get chips out. Do not use grease on tap as it will trap chips inside of cylinder. Everyone has their own way. Best way would be to remove head and have a quality cylinder head guy repair it. But sometimes cost is more than people want to pay. I use a green loc tite bearing retainer that is for high heat to retain inserts in head and have never had one failure. They recommend jb weld but I have never used it...Good luck.