Champion RN9YC Spark Plug

The Champion RN9YC was the specification spark plug for virtually every American V8 engine from the 1960s through the 1990s. General Motors specified Champion in the Corvette C1/C2, Pontiac GTO, and Chevrolet Bel Air; Ford used Champion in the Mustang and Thunderbird. The "R" prefix denotes a resistor plug; "N" is the 14 mm thread family; "9" is heat range; "YC" is the specific electrode configuration for high-energy ignition. The interchangeability of Champion plugs across all GM and Ford small-block V8s meant any mechanic needed only one spark plug type for American muscle cars.