.40 DiamondFIRE Spark Plug

The E3.40 Automotive Spark Plug is a direct replacement designed for various domestic applications from the 1960s to the early 1990s. It features a 14mm thread diameter, a 0.460-inch thread reach, and a taper seat, with a 5/8-inch hex size for installation. The plug incorporates E3's patented DiamondFIRE technology, utilizing a three-legged electrode design that aims to enhance heat transfer and promote greater turbulence within the combustion chamber. This construction is claimed to yield benefits such as increased power output, reduced fuel consumption, and improved hydrocarbon emissions over the long term. The E3.40 also features a unique ground electrode and a full-size center electrode. E3 guarantees optimal performance for a period of five years or 100,000 miles. This spark plug is a resistor type and has a fixed DiamondFIRE gap that cannot be adjusted.