Champion 405 Spark Plug

Champion Copper Plus 405 Spark Plug

Champion Copper Plus 405 is a replacement spark plug built for dependable ignition performance and stable heat control. Its copper core electrode improves conductivity, while nickel-based electrode materials support consistent wear characteristics for everyday driving and classic vehicle service.

Key Features

• Copper core electrode for improved conductivity and heat transfer
• Nickel center electrode tip and nickel ground electrode core material
• Pre-gapped at 0.035 in. / 0.90 mm
• Resistor type plug for ignition system noise control
• Flat seat design with 0.75 in. reach and 14 mm thread diameter
• Champion Copper Plus classification, part number 405

Product Details

The Champion Copper Plus line focuses on straightforward, OE-style ignition service, and this 405 spark plug follows that approach with a copper core for conductivity and heat management. The RN14YC plug type, flat seat, and 0.035-inch pre-gap make it a practical choice for older import and domestic applications that call for this specification. This part cross-references Autolite 66 and NGK 4224 for the same application.

Compatible With applications such as 1985-1987 Honda Civic, 1981-1988 Jeep J10, 1981-1988 Jeep J20, 1986-1991 Mercedes-Benz 560SEC, and 1989-1994 Pontiac Sunbird. It also appears in fitment for classic Chrysler, Dodge, BMW, Bentley, Rolls-Royce, and Toyota Land Cruiser applications where RN14YC specifications are required. Champion 405 is a direct-fit service plug for many vehicles across the 1954-1994 model years listed in the fitment data.

Common Uses

• Restoring weak spark or inconsistent combustion
• Replacing worn plugs with excessive electrode wear
• Addressing rough idle or misfire conditions tied to plug condition
• Maintaining proper ignition performance in older OE-style applications
• Servicing vehicles that specify RN14YC plug type and 0.035-inch gap

Installation Notes

Verify the required plug type, seat style, thread diameter, reach, and heat range before installation. The plug is pre-gapped at 0.035 in., but the vehicle specification should always be checked against the service manual for the exact application. Use proper torque procedures and inspect ignition wires, coils, and distributor components during replacement to avoid repeat misfire issues.

Quality Assurance

Champion Copper Plus plugs are built around a copper core design for conductivity and heat control, with nickel electrode materials for dependable service life in the applications listed. Part number 405 is engineered to match the RN14YC specification used across a wide range of classic and late-20th-century vehicles.