Manley Chevrolet Big Block Exhaust Valve Kit - 1.940in Head Dia. 5.522in O/A Length, 0.3110in Stem

This kit includes Manley's Severe Duty? exhaust valves, specifically designed for Chevrolet Big Block engines. Each valve features a 1.940-inch head diameter, a 5.522-inch overall length, and a 0.3110-inch stem diameter. These valves are crafted from XH-428 material, a choice that Manley states offers nearly double the ultimate tensile strength at 1500°F compared to other common exhaust valve materials like EV-8.

Manley's Severe Duty? valves are built for high-temperature gasoline engines and have undergone extensive fatigue testing. In tests simulating valve bounce on the seat, where stress can reach 40,000 to 60,000 lbs, these exhaust valves endured up to 100 million cycles at 40,000 psi and 1400°F. This is a notable improvement over competitor valves that failed much sooner. The under-head areas are swirl-polished, and the combustion faces are fully machined to help improve airflow and combustion efficiency. They also feature chrome stems and hard tips for added durability.