Manley 11721-8 Extreme Duty Exhaust Valve Small Block Chevy 1.625

These valves are an excellent choice for bracket racing, oval track, and high-performance street engines.

Engineered to meet the demanding needs of Top Fuel and Funny Car drag racers, Big Block Chevy marine enthusiasts, and Small Block Chevy restricted carburetor circle track competitors.

Key Specifications:

• Head Diameter: 1.625 in.
• Stem Diameter: 0.3415 in.
• Overall Height: +0.300 in. longer than stock
• Application: Small Block Chevy Exhaust

Key Features:

• XH-432 XtremeAlloy construction — the hallmark of excellence in exhaust valve material.
• Stainless steel construction with chrome stems and hardened valve tips.
• Swirl-polished under-head areas and fully machined combustion faces improve airflow and combustion efficiency.
• Valve stems are hard-coated with .0002" thick chrome rather than a few millionths of flash.
• Hard valve tips are superior to competitors' puddled stellite, which can crack and erode off the stem.

These valves are designed to withstand extreme combustion pressures, high temperatures, and aggressive cam profiles, with back-cut designs for improved airflow and hardened tips for added longevity — optimizing power output in naturally aspirated, forced-induction, and nitrous-fed applications.