Speedmaster DNA Aluminum Roller Rocker Arms Set 1.65 Ratio 7/16" for Holden 253 304 308

The Speedmaster DNA Aluminum Roller Rocker Arms Set (MPN 1-261-009) is a precision-engineered rocker arm assembly designed for Holden 253, 304, and 308 engine applications. This set features a 1.65 ratio and 7/16" stud size, offering direct fitment for vehicles equipped with these classic Holden engines. The DNA aluminum construction provides a lightweight alternative to cast iron, reducing overall engine mass while maintaining structural integrity for reliable performance.

These roller rocker arms deliver improved valve train efficiency through reduced friction and wear compared to traditional stamped or solid rocker designs. The 1.65 ratio lifts the valve higher per unit of cam lobe travel, enhancing volumetric efficiency and airflow characteristics. The complete set ensures proper valve actuation and is ready to install on compatible Holden engine blocks, making it an ideal upgrade for engine rebuilds, performance modifications, or stock replacement applications where improved durability and efficiency are desired.

Key Features & Benefits

• 1.65 Ratio Design: Optimized valve lift ratio for increased volumetric efficiency and improved airflow.
• DNA Aluminum Construction: Lightweight aluminum alloy reduces rotating mass while maintaining durability.
• 7/16" Stud Size: Direct compatibility with Holden 253, 304, and 308 engine specifications.
• Roller Design: Roller tips reduce friction and wear compared to flat-tappet designs.
• Complete Set: Includes all rocker arms needed for full engine valve train assembly.

Specifications

Ideal Applications

• Engine rebuilds for classic Holden vehicles
• Performance modifications to improve valve train efficiency
• Stock replacement rocker arm assemblies for Holden engines
• Cylinder head assembly upgrades on 253, 304, 308 platforms