Spark Plugs - '48-'74 Big Twin

Plugs have a unique look with their black ceramic body and bold red logo/script. Insulator is made of 95% pure alumina and features strong resistance to heat shock and superior insulation. Multi-rib design of insulator eliminates flashover. Nickel-plated housing prevents oxidation and corrosion. Multi-layer gaskets and heat-crimping process ensure a leak-free, gas-tight fit. Copper core electrode prevents oxidation and corrosion and has good electrical and heat conductivity for long spark plug service life.