685 Spark Plug

The Champion 685 spark plug is a premium non-resistor racing plug engineered for high-performance engines that demand precise ignition timing and maximum spark energy. Built for automotive enthusiasts and professional mechanics working with fuel-injected and carbureted performance builds, this Champion Racing plug delivers consistent combustion when standard plugs fall short. Whether you're tuning a vintage muscle car, optimizing a street rod, or calibrating a competition engine, the 685 provides the reliable fire your application requires for peak horsepower and efficiency.

The 685 features a tapered seat design with a 14 mm thread diameter and 0.689 inch reach, allowing direct fitment into engines engineered for this geometry without heat-range compromise. As a non-resistor plug, it eliminates secondary resistance that can suppress spark voltage in high-output applications, delivering full ignition energy to the combustion chamber. The robust construction and precise electrode gap tolerances ensure repeatable firing characteristics across cylinder banks, critical for carb tuning and EFI systems alike. This design proves invaluable when engine modifications—larger displacement, higher compression, or exotic fuel blends—demand superior spark intensity and heat dissipation.

Mechanics and engine builders favor the Champion 685 for applications where OEM resistor plugs introduce unwanted electrical losses. Verify your engine's original equipment specifications or consult your tuning data sheet to confirm the 14 mm thread and 0.689 inch reach match your cylinder head casting. Installation requires standard 5/8-inch or 13/16-inch spark plug socket and proper gap setting per your fuel system and ignition calibration. Stock this non-resistor as part of your race preparation kit or keep on hand for immediate replacement during performance development and dyno tuning sessions.