Designed and manufactured by Heli-Coil® to provide specific and unique benefits to high-temperature, high-performance spark plug applications.

Heli-Coil® spark plug screw thread inserts are manufactured from 18-8 round stainless steel wire formed into a 60° diamond-shaped wire. This cold-worked wire, which has a tensile strength of 200,000 PSI, is wound into a helical coil with a driving tang and notch to remove the tang after the insert is screwed into the Heli-Coil® tapped hole.

In its free state, the insert is larger in diameter than the tapped hole. Once installed, the insert assumes the configuration of the tapped hole. The resulting outward spring-like action anchors the insert in place. The Heli-Coil® spark plug insert becomes an integral part of the cylinder head, providing high-strength threads which exceed the surface smoothness, hardness, and accuracy of any threads tapped in any material.

Fast Facts:

  • Serrated top coil which is offset and staked into the parent material.
  • Easier spark plug removal because of limited corrosion possibility.
  • Eliminates thread failure due to stripping, vibration, and fatigue.
  • Extends thread life, even after repeated disassembly and reassembly.
  • Greatly increases tapped thread strength under all operating conditions.
  • Speed and economy in production salvage, providing greater-than-original thread strength.

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The availability of the products described on this site, and the product descriptions, may vary from country to country. Consult your STANLEY® Engineered Fastening Account Executive or your local distributor for specific product information.