Question: Will my fully threaded spark plugs (all the way up to the taper) work with the inserts that come in the kit which have threads only about 1/2 way?

Answer: Yes they will. If preferred, we also have fully threaded inserts (PN 51457) which have twice the number of threads for more holding power. *Note that partially threaded plugs will NOT install properly in the 51457 fully threaded insert so the inserts included in the kit have to be used. These inserts are still much stronger than the original aluminum threads. 

Time Sert 5553 Description Video

More questions answered in our video series below, like - Which is the best brand? How do you determine the valves are closed and why does it matter? 

Below is a video demonstrating how the Time Sert 5553 kits is basically used.