Manley Chevrolet Small Block Exhaust Valve Kit - 1.600in Head Dia. 4.950in O/A Length, 0.3136in Stem

These Manley Severe Duty exhaust valves are built from XH-428 material, a choice that offers nearly double the ultimate tensile strength at 1500°F compared to common EV-8 materials. This makes them a solid option for high-temperature gasoline engines where durability under stress is critical. Each valve measures 1.600 inches across the head and has an overall length of 4.950 inches, with a 0.3136-inch stem diameter, designed to fit Chevrolet Small Block engines.

Manley subjected these valves to rigorous fatigue testing, simulating extreme conditions where valve bounce can dramatically increase stress. While typical valves might fail after 100,000 cycles under such stress, these Manley exhaust valves endured up to 100 million cycles at 40,000 psi and 1400°F. They also feature chrome stems and hard tips for added wear resistance, and the under-head areas are swirl polished to help improve airflow and combustion efficiency.