Manley Chevrolet Big Block Intake Valve Kit - 2.250in Head Dia. 5.594in O/A Length, 0.3110in Stem

The Manley Performance 12898-8 Severe Duty™ Valves are designed for superior performance in high-temperature gasoline engines. These valves have undergone rigorous fatigue tests, enduring up to 100,000,000 cycles at 40,000 psi and 1400°F, significantly outperforming competitors whose offerings failed after 100,000 cycles. They feature chrome stems and hard tips for enhanced durability and longevity. Optimized combustion is achieved through swirl polished under head areas and fully machined combustion faces, improving airflow and combustion efficiency. Manley's exhaust valves utilize XH-428 material, boasting nearly double the ultimate tensile strength at 1500°F compared to competitors' EV-8. The intake valve material, NK-844, exhibits over four times the ultimate tensile strength of the competition's best intake valve material at 1000°F.