Valve - Intake

Manley Severe Duty® Valves deliver the ultimate in strength, reliability, and high-performance durability. Engineered for extreme gasoline engine temperatures, these valves are crafted from exclusive materials (XH-428 for exhaust and NK-844 for intake), offering unmatched tensile strength compared to competitive alloys. In fatigue testing at 40,000 psi and 1400°F, Manley exhaust valves endured 100 million cycles, while competitors failed after just 100,000, proving a 1,000× longer fatigue life. Each valve features chrome stems, hard tips, and swirl-polished underheads with fully machined combustion faces for superior airflow, efficiency, and wear resistance. Built for those who demand race-winning strength and precision, Manley Severe Duty® Valves set the industry standard for performance and endurance.

Part Type

Engine Intake Valve

• Chrome stems and hard tips enhance durability
• Exotic alloys for superior tensile strength, reliability, and longevity
• Proven fatigue strength for extreme performance
• Swirl polishing and machined faces improved airflow/optimized efficiency

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Reference Information

Valve, Intake, Stainless Steel, 4.730 in. Length, 1.775 in. Diameter, 0.3415 in. Diameter Stem, Buick V6, Set of 6

Manley Severe Duty Pro Flo Series intake and exhaust valves are a great choice for your high performance or race engine. All valves are made from stainless steel (intakes are NK-844; exhausts are XH-428) with chrome stems and hardened valve tips. Severe Duty series valves are fully machined and swirl polished, and offer improved flow with undercut "Pro Flo" stems. Many size options are available, for applications from 1955 and up.