Manley Chevrolet Small Block Exhaust Valve Kit - 1.625in Head Dia. 5.640in O/A Length, 0.3110in Stem

If you're rebuilding the top end of your Chevrolet small block engine, these exhaust valves from Manley Performance are a solid option. They're specifically made for high-temperature gasoline engines and feature a 1.625-inch head diameter and a 5.640-inch overall length, with a 0.3110-inch stem diameter. These aren't just any valves; they're constructed from XH-428 material, which Manley states has nearly double the tensile strength at 1500°F compared to other common exhaust valve materials.

What really sets these valves apart is their durability under stress. Manley subjected them to rigorous fatigue tests, simulating extreme conditions where valves can bounce on the seat. Under these harsh tests, at 40,000 psi and 1400°F, these valves impressively lasted up to 100 million cycles. For comparison, other valves in the test failed after only 100,000 cycles, showing a remarkable difference in fatigue life. They also feature chrome stems and hard tips for added wear resistance, and the under-head areas are swirl-polished to help improve airflow into the combustion chamber.