Olds 403 / 1977-79 Trans Am

Awakening the Olds 403: Performance Upgrades for the '77–'79 Trans Am at Butler Performance

The All-In-One Power Solution: Top End Package

The most effective way to wake up the Olds 403 is by addressing its greatest weakness: restricted airflow and low compression. Butler Performance has engineered a comprehensive Hydraulic Roller Top End Power Package to simplify this process:³

• Integrated Design: This package is a complete, bolt-on system, eliminating the guesswork of mixing and matching components.⁴ It is capable of pushing a 403 V8 to upwards of 390hp 405lb-ft of torque.⁷

   

   

• Modified Cylinder Heads: The package features Edelbrock Big Block Olds Heads that are expertly milled to fit the 403 small block.⁸ This is a critical modification that increases the compression ratio—a necessity for modern performance.

   

   

• Custom Camshaft: Included is a Butler/COMP custom-grind hydraulic roller camshaft and a set of performance lifters (such as COMP Cams Evolution Hyd. Roller Lifters) to drastically improve valve lift and duration.

• Port-Matched Intake: An Edelbrock Performer RPM Intake Manifold is supplied and port-matched in-house by Butler Performance, ensuring seamless airflow transition to the prepared cylinder heads.⁹

   

   

Individual Component Upgrades

For builders customizing their approach, Butler Performance offers high-quality individual components designed for the Olds 403:

Valve Covers and Aesthetics

• Custom CNC Aluminum Valve Covers: Butler provides custom CNC Logo Aluminum Valve Covers for the 403 Olds.¹⁰ These covers not only add a high-end, finished look to the engine bay but also offer increased internal height to accommodate performance valvetrain upgrades like stud girdles or roller rockers.

   

   

Distributor and Ignition Reliability

The Olds 403 has specific distributor gear requirements, especially with high-performance roller camshafts.

• Polymer Distributor Gears: Butler offers Polymer Distributor Gears in various diameters .491 and .500 to ensure compatibility.¹³ The polymer material is critical when running a roller cam to prevent premature wear on the distributor gear.

   

   

Critical Sealing and Cooling

• Viton Rear Main Seal: Butler offers a modern, two-piece Viton Rear Main Seal to replace the leak-prone factory rope seal, a common failure point in older V8s.¹⁴

   

   

• High-Volume Water Pump: Flowkooler Hi-Volume Aluminum Water Pumps with CNC machined billet impellers are available for both A/C and non-A/C equipped engines, ensuring the upgraded 403 maintains optimal temperature under hard driving.¹⁵

   

   

Maintaining the Icon: Trans Am Shaker Fitment

Upgrading the Olds 403 in a Trans Am requires careful consideration of the iconic Shaker Hood Scoop.

• Intake Height Impact: Swapping to a taller performance manifold like the Performer RPM (a common component in Butler's kits) will cause clearance issues.

• Drop Base Solution: Butler Performance addresses this by offering PTF Drop Base Shaker Units.¹⁶ These components lower the air cleaner assembly by approximately $1\text{"}$, allowing the shaker to sit correctly and function properly with the taller performance intake manifold.

   

   

By focusing on the specific needs of the Olds 403—from correcting its breathing and compression issues to providing critical chassis fitment accessories—Butler Performance has established itself as the premier resource for transforming the late-'70s Trans Am into a modern muscle machine.