Champion 400 Spark Plug

Champion Copper Plus 400 Spark Plug

Champion Copper Plus 400 is a tapered-seat spark plug built for dependable ignition performance in a wide range of classic Chevrolet, Ford, Buick, Pontiac, GMC, and Oldsmobile applications. The copper core electrode supports conductivity and heat control, while the nickel center and ground electrode materials help maintain consistent wear characteristics.

Key Features

• Copper core electrode for improved conductivity and heat management
• Nickel center electrode tip and nickel copper alloy ground electrode
• Pre-gapped at 0.035 in. for many listed applications
• Resistor-type design for ignition system noise control
• Tapered seat construction with 14 mm thread diameter
• Removable nut terminal for flexible connection styles
• Champion Copper Plus Small Engine classification

Product Details

The Champion 400 spark plug is part of the Copper Plus line, a product family focused on straightforward, dependable ignition service. This plug uses a copper core to improve heat transfer and conductivity, which helps support stable combustion and consistent wear over time. The tapered seat, 0.441 reach, 0.625 hex size, and resistor design make it a practical OE-style replacement for many older GM and Ford engines. Part number 400 is also referenced by RV9YC applications, making it a useful match for drivers searching for a Champion RV9YC spark plug or a Champion 400 spark plug for classic vehicle maintenance.

Compatible With applications such as 1985-1987 Chevrolet Camaro, 1982-1993 Chevrolet S10, 1982-1986 Buick Century, 1985-1988 Pontiac Fiero, and 1970-1971 Ford Mustang. This part cross-references Autolite 23 and Four Seasons 33400 for the same application.

What It Helps Address

• Hard starting caused by worn or inconsistent spark plugs
• Rough idle from weak ignition output
• Misfire concerns related to electrode wear
• Heat-related plug performance issues in older engines
• Service replacement needs for OE-type RV9YC applications

Installation Notes

Verify the required plug type, seat style, thread diameter, reach, and gap before installation. The listed pre-gap is 0.035 in., but several vehicle applications call for different gap settings, so confirm the engine specification and adjust as needed. Use the removable nut terminal only if your ignition lead requires that configuration. For best results, inspect the ignition wires, coil condition, and cylinder head threads during service.

Quality Assurance

Champion Copper Plus plugs are built around a copper core design for conductivity and heat control, with nickel-based electrode materials for steady wear characteristics. Part number 400 is engineered to meet the dimensional and electrical requirements shown in the product data for listed applications, including Chevrolet Camaro, Chevrolet S10, and Ford Mustang fitments.