Dover Cylinder Head - Atlanta, Georgia

(404) 768-1825 - (800) 541-1767

GM 5.7 350 L31 Series 1996 and up - VIN Code 'R'

Replaces Cylinder Head Casting Numbers: 12558062 & 10239906

All New Cylinder Head Casting & Components

Premium Grade Cast Iron with Redesigned Water Jacket for Enhanced
Thermal Conductivity and Increased Resistance to Cracking

Close Tolerance Casting and Machining for Precise Component Fit
Providing the Best in Performance and Durability

Completely Assembled - Ready to Bolt On

Includes All New:

• Pro Topline Cylinder Head Casting
• Valves
• Valve Springs
• Valve Spring Retainers
• Fluoroelastomer Valve Stem Seals
• Hardened Valve Locks
• Screw-in Rocker Arm Studs

• Intake Valves - 1.940
• Exhaust Valves - 1.500
• Exhaust Seats - Hardened Inserts
• Combustion Chamber - 64cc Heart Shaped
• Intake Runner - 170cc LT1 Hi-Flow (Same as Phase 2)
• Heat Riser - None
• Spark Plug Angle - Straight
• Valve Cover - Center Bolt Only
• Rocker Studs - Screw in 7/16-14
• Uses OE Self-Aligning Rocker Arms