I know everyone has been there. Striped a thread or two out of a block etc... Everyone always reaches for the cheap quick fix of a heli-coil. Nothing wrong with that but if you like the piece of mind and a strong insert system that you can use many many times please look up timeserts. They have saved me on multiple occasions. Im using a set of Flathead heads as a demo to show you the process. They make the kits in almost any thread size under the sun. So enjoy! Heres the head I started with Here is the buggered up spark plug hole. A previous owner had heli-coiled every hole and used all different depths. So out those came. Heres the head and what you get in the kit. There is a wrench, The seat cutter, The threading tap, the insert tool and the timeserts themselves. Here is the spark plug tap. It has a special pitch, you can not use a standard tap in these. Mine went in pretty easy seeing the hole was slightly oversized from the heli-coil tap. Remember to use a cutting fluid of your choice. Now run the tap all the way down alittle lower than flush with the top of the hole. I got two turns. Leave the tap in place becuase the seat cutter uses the tap for centering. Now slide the seat cutter tool over the tap and set the wrench into the slot of the cutter. Once you have turned the seat cutter around a few times, it will be ready to be removed. I also use a bit of cutting fluid for this too. Now you are ready for the insert. Now oil up your insert tool and screw the timesert on the end. I do it this way it makes it easier to start, but some people hand screw it in the hole then place their oiled insert tool into it. Now screw the insert all the way down. the seat in the head will stop on the seat on the insert. From this point on the turning action will get a little harder. What the tool is doing is forming the last few threads forcing the insert to expand into (in this case) the aluminum head. And here is the final product, ready for a spark plug. Very easy, very simple instal. I take my time and use lots of oil and make sure the keep everything clean. Hope you enjoyed this simple tech and hope I turned a few people on to this great helpful product.