Use this tool, you will not have to remove the plug and measure it.
Use this tool with a cam degree wheel to dial in the cam for maximum horsepower.
14-K919A 10mm (uses NGK plugs beginning with C)
14-K919B 12mm (uses NGK plugs beginning with D)
14-K919C 14mm (uses NGK plugs beginning with B)
N.W. : 0.11 kg/pc.
