Champion Racing Plug Number C57 Spark Plug - 686 Part #: 686 Line: CHP Champion Racing Plug Number C57 Spark Plug 1 Year Limited Warranty Seat: Gasket Thread Size: M14 Heat Range: 57 Hex Size (in): 5/8 Inch Preset Gap (in): 0.025 Inch Preset Gap (mm): 0.65mm Center Electrode Tip Material: Nickel Ground Electrode Tip Material: Nickel Service Number: C57 Metallurgy: Copper Show More Show Less