What makes Heli-Coils so good is their unique design. The wire is diamond shaped ... You don’t need any kind of threadlocker with a Heli-Coil, as they do not come out easily.

We’ll show you step-by-step how each system works and recommend when you should use them. HeliCoil makes stainless steel, spring-like thread inserts that replace the original threads.

and then the spark plug screws into the Heli-Coil. Got it? RAY: But it doesn't always work. Sometimes the hole is badly damaged to begin with, or sometimes, because of the design of the engine ...