Manley Chevrolet Big Block Exhaust Valve Kit - 1.900in Head Dia. 6.450in O/A Length, 0.3415in Stem

Starting with the XH-428 material for the exhaust valves, Manley Performance has developed a Severe Duty? valve kit designed for the rigors of high-temperature gasoline engines. These aren't your average replacement parts; they're built to handle the intense stresses and heat found in performance and racing applications. The XH-428 material itself is notable, offering nearly double the ultimate tensile strength at 1500?F compared to common EV-8 materials used by competitors.

Beyond the material, these valves feature chrome stems and hard tips, adding layers of durability and ensuring they stand up to repeated use. The under-head areas are swirl polished, and the combustion faces are fully machined. This attention to detail helps optimize airflow and improve combustion efficiency, making a real difference in how your engine performs. Manley has put these valves through extensive fatigue testing, simulating extreme conditions where valves can experience up to 60,000 lbs of stress. Under these harsh tests, at 1400?F, these valves endured up to 100 million cycles, a performance that far outlasts many competitor offerings.

This kit includes eight exhaust valves, each measuring 1.900 inches in head diameter and 6.450 inches overall length, with a 0.3415-inch stem diameter. If you're rebuilding a Chevrolet big block engine and demand components that can withstand extreme heat and stress, these Manley Severe Duty? valves are a solid option.