well being a machinist myself, there isn't a whole lot of skill involved in installing a Heli-Coil, but there are a couple of things you want to remember. When you get the kit, it tells you exactly what size to drill the stripped hole out to. You'll wanna do that in a drill press. A press is square enough. Don't do it by hand. Use a good Cutting Fluid, not oil. CUTTING FLUID to run the Heli-Coil tap. Take your time with it. Turn the tap 3/4 of a turn in, and back out a 1/4 turn. Once it's finished cutting, remove the tap and clean the chips away completety from the head and the tap, and run the tap thru again. Clean once more. Install the insert. Lockite in place and you're ready for a glow-plug. Now if you stripped out the threads in your head, remember it's not a "head-bolt" it's a glow plug. Doesn't take a whole lot of torque to set one of those. When you instal a Heli-Coil, you want to be even more careful not to over torque. You strip that puppy out and you're looking at a new head, or at least a weld repair and then ya need ya a Machinist.