COMP Cams 1478-1 GM LS3 1.7 Ratio Rocker Arm with Trunnion Upgrade Kit

The COMP Cams 1478-1 is a factory-ratio rocker arm assembly designed for GM LS3 engines, featuring a critical trunnion upgrade that addresses one of the most well-known reliability weaknesses in the LS valvetrain. These rockers retain the stock 1.7:1 ratio while incorporating upgraded trunnion bearings and needle rollers in place of the factory press-fit trunnion pins — a modification that dramatically improves durability under sustained high-RPM operation and performance use.

Key Features:

• Direct factory-replacement rocker arm for GM LS3 applications
• 1.7:1 rocker ratio — maintains stock valve lift characteristics
• Upgraded trunnion assembly with needle roller bearings for reduced friction and improved longevity
• Eliminates the factory press-fit trunnion pin design prone to premature wear and failure
• Compatible with stock and mildly upgraded LS3 valvetrain components
• Manufactured by COMP Cams to OEM fitment specifications

The trunnion upgrade found in the COMP Cams 1478-1 is a popular and often recommended modification for LS3-equipped vehicles used in performance driving, towing, or any application where the engine sees extended high-load cycles. By replacing the failure-prone factory trunnion with a properly supported needle bearing design, these rocker arms deliver reliable performance with improved heat and wear resistance over the stock units.