Manley Chevrolet Big Block 2.300 Head, .3415 Stem, .350 Longer Severe Duty Valves (Set of 8)

If you're rebuilding the top end of a Chevrolet Big Block engine and need valves that can handle serious stress, these Manley Severe Duty valves are a solid option. They're designed to be .350 inches longer than stock, which can be helpful when working with modified cylinder heads or specific camshaft profiles. The set includes eight valves, four for intake and four for exhaust, each built with specific materials to withstand high temperatures and heavy use.

Manley uses XH-428 material for the exhaust valves, which they say has nearly double the tensile strength at 1500°F compared to other common exhaust valve materials. For the intake valves, they use NK-844 material, which boasts over four times the tensile strength of competing intake valve materials at 1000°F. These materials, combined with swirl-polished under-head areas and machined combustion faces, help improve airflow and combustion efficiency. The chrome stems and hard tips add to their durability, and rigorous fatigue testing shows these valves can endure up to 100 million cycles under demanding conditions, far outlasting many competitors.

These valves are a good choice for high-temperature gasoline engines where reliability under stress is crucial. Make sure to check your cylinder head and valve spring compatibility to ensure these .350 longer valves will work correctly with your build.