Review on Heli Coil R51313 14 1 25Mm Inserts Pk by Dustin Miller

Works great. If you have a larger hole from a gem bladed insert, use that, thread it into the threads, make sure it's snug, then insert the timing bar into the spark plug before screwing it in. You don't have to spend $500 to buy a large certificate. by Timesert I guarantee you it will work great. Make sure you need to tap the hole with a 14mm 1.25 spark plug tap.