Manley 12856H-8 Severe Duty 2.250" +.250 Hollow Stem Intake Valve

Designed for high-performance and racing applications, these valves are built to withstand the extreme stresses of bracket racing, oval track competition, and demanding high-performance street use.

Key Features:

• Hollow Stem Design: Reduces reciprocating valve train mass for improved high-RPM performance and reduced spring seat pressure requirements
• NK-844 Stainless Steel Construction: Intake valves are manufactured from NK-844 stainless steel, offering exceptional tensile strength and heat resistance far exceeding conventional intake valve materials
• Chrome Stems: Hard chrome-plated stems provide superior wear resistance and reduced guide friction for extended service life
• Hardened Valve Tips: Hardened tips resist rocker arm wear and maintain valve train geometry under sustained high loads
• Swirl Polished Under-Head Area: Optimizes airflow past the valve head for improved volumetric efficiency
• Fully Machined Combustion Face: Precision-machined seating surface ensures consistent sealing and optimal combustion chamber geometry
• +.250" Oversize Head Diameter: Allows use in cylinder heads that have been machined for larger valve pockets, maximizing intake flow potential

Manley Performance is a leading manufacturer of performance and racing engine valves. The Severe Duty series represents their premium stainless steel valve line, engineered to deliver consistent performance and long service life in demanding race and high-performance street environments. Part number 12856H-8 is the hollow stem variant of the 12856 series, ideal for builds where reducing valvetrain weight is a priority.