Manley 12737-8 Extreme Duty Exhaust Valves Big Block Chevy 1.880" Head 11/32" Stem +.100"

Built from Manley's exclusive XH-432 XtremeAlloy material, these valves deliver outstanding high-temperature strength that ordinary stainless steel valves simply cannot match, making them ideal for applications including Top Fuel, Funny Car drag racing, big block marine engines, and restricted carburetor circle track competition.

Each valve features a 1.880" head diameter and an 11/32" (0.3415") stem diameter, with an installed height that runs +.100" longer than stock for precise valvetrain geometry. The overall length measures 5.522", with a 0.250" tip length. The underhead angle and radius is 18° x 1/2", the margin is 0.075", seat width is 0.085", and the top of head features a 12° dish profile. Each valve weighs 134 grams.

Key Features:

• XH-432 XtremeAlloy construction — Manley's proprietary exhaust valve material for extreme heat resistance
• Hard-coated chrome stems — .0002" thick chrome coating for superior wear resistance and longevity
• Hard valve tips — superior to puddle-welded alternatives that can crack or erode
• Swirl-polished underhead areas and fully machined combustion faces for improved airflow and combustion efficiency
• 1.880" head diameter with 11/32" stem diameter
• +.100" over stock installed height — 5.522" overall length
• 18° x 1/2" underhead angle/radius with 12° dish top of head

Manley Performance has been a trusted name in racing and performance engine components since 1966. The Extreme Duty series represents the pinnacle of their valve engineering, offering the heat and fatigue resistance demanded by the most punishing engine builds. MPN: 12737-8.