A special thread and shell coating ensures quick and easy removal from aluminum heads and resists corrosion. A gold palladium insert extends life and improves resistance to corrosion. The tapered tip provides better spark exposure to air/fuel mixture and allows the mixture to flow more easily through gap area for maximum combustibility. Fouling resistance is improved with smaller diameter center electrode wire and insulator tip. Plus, a copper-cored ground electrode runs cooler for extended life.