• Precision CNC porting: 260cc intake, 100cc exhaust, and 69cc combustion chambers
• Premium Virgin A356 aluminum construction
• Reinforced 6-bolt head design for superior durability
• Optimized 11° valve angle for peak airflow and piston-to-valve clearance
• High-performance 2.165” intake valves (21-4N alloy) & 1.60” exhaust valves (23-8N super alloy)
• Generous valve free drop: 0.210" intake, 0.250" exhaust
• 23-8N alloy offers Inconel-like heat resistance minus the fragility
• Options available: fully assembled with Chromoly or titanium retainers, or bare heads with valves
• Includes billet rocker arm stands, fully compatible with factory LS3 rockers
• Fits 4-bolt factory engine blocks — requires a minimum bore of 4.000"
• Pricing reflects a complete set

Spring Specifications (0.660”):

• Seat Pressure: 145 lbs @ 1.800"
• Open Pressure: 400 lbs @ 1.130"
• Coil Bind: 1.070"

Spring Specifications (0.700”):

• Seat Pressure: 170 lbs @ 1.800"
• Open Pressure: 450 lbs @ 1.115"
• Coil Bind: 1.000"

Flow Bench Insights: Tested at 28inHg, with a 4.125" bore, radius entry on intake, and open exhaust port. Please keep in mind that flow numbers alone do not determine cylinder head performance. Real engine environments feature dynamic air and fuel movement — not static conditions like in flow tests. Our 11° design excels under actual engine loads, surpassing even some 12° models despite their advertised higher flow rates. In direct dyno tests with a 441" LS engine and our R4 Stroker cam, these heads delivered superior power consistently across the RPM range.