These are the most commonly used performance plugs today! These are a stock replacement for Mercruiser BBC and SBC motors.
Ribbed Suppressor Seal, which extends resistance and prevents spark 'flash over' and misfire. Nickel-chrome alloy sheathing to help prevent corrosion on center electrode.
Heat Range: 3
Resistor Plug: Yes
Gap (In): 0.040 Inch
Thread Reach (In): 0.430 Inch
Note: Colder plugs work best in supercharged applications and warmer plugs in general performance uses. Most cast iron cylinder heads use tapered spark plug while most aluminum heads use a gasket style plug.