Champion Racing Spark Plug - 683 Part #: 683 Line: CHP Champion Racing Spark Plug 1 Year Limited Warranty Seat: Tapered Thread Size: M14 Heat Range: 59 Hex Size (mm): 16mm Hex Size (in): 5/8 Inch Preset Gap (in): 0.025 To 0.650 Inch Preset Gap (mm): 0.58mm To 0.71mm Thread Reach (in): 0.689 Inch Resistor Plug: No Center Electrode Core Material: Nickel-Copper Alloy Center Electrode Tip Material: Nickel Ground Electrode Tip Material: Nickel Show More Show Less