Manley 11359-8 Severe Duty Exhaust Valve Kit 1.600" Head, 0.311" Stem

These valves are crafted from Manley's exclusive XH-428 exhaust alloy, a proprietary stainless steel formulation that delivers tensile strength and heat resistance far beyond conventional alloys. In fatigue testing at 40,000 psi and 1,400°F, Manley's exhaust valves completed 100 million cycles — compared to just 100,000 cycles for competing valves — demonstrating a 1,000× advantage in fatigue life. Each valve measures 1.600 inches in head diameter, 5.540 inches in overall length, and 0.3110 inches in stem diameter, with a 9-degree dish head profile, 15-degree underhead angle, and a 1/2-inch underhead radius.

Key Features:

• Exclusive XH-428 stainless steel alloy for superior tensile strength, reliability, and longevity under extreme temperatures
• Proven fatigue strength: 100 million cycles at 40,000 psi and 1,400°F in independent testing
• Chrome-plated stems and hard tips for enhanced wear resistance and durability
• Swirl-polished underheads and fully machined combustion faces for optimized airflow and efficiency
• Head diameter: 1.600 in. | Overall length: 5.540 in. | Stem diameter: 0.3110 in.
• Tip length: 0.290 in. | Margin width: 0.080 in. | Seat width: 0.100 in.
• 9-degree dish head shape | 15-degree underhead angle | 1/2 in. underhead radius
• Kit includes 8 exhaust valves

Manley Severe Duty® Valves are built for engine builders and performance enthusiasts who demand race-proven strength and precision in every component. Designed for small block Chevrolet applications, these valves set the benchmark for high-performance exhaust valve endurance and consistency.