Crankshafts

1. Stock vs. Stroker: Maximizing Displacement

The decision to use a stock-stroke or a stroker crankshaft is the first step in defining an engine’s character.

• Stock Stroke: Pontiac V8s came with strokes ranging from $3.75$ inches (400 blocks) to $4.21$ inches (455 blocks). While reliable, these are best suited for street engines and restorations.

• Stroker Crankshafts: Butler Performance is famous for building large-displacement Pontiacs. A stroker crank increases the stroke length, dramatically increasing cubic inches and, consequently, torque.

   

  • The Power Upgrade: Using a $4.250$ inch stroke crank in a standard 400 block creates a formidable $461\text{ci}$ to $467\text{ci}$ engine.

     

  • Max Displacement: In a 455 block, a stroker crank can easily push displacement to $468\text{ci}$ or even $503\text{ci}$.

  • In an Aftermarket IAII block, a stroker crank can easily push displacement to $505\text{ci}$ or even $535\text{ci}$.

Butler's Recommendation: For any performance build intended for street/strip or racing, increasing the stroke is the most efficient way to maximize horsepower potential and low-end torque.

2. Material: Nodular Iron vs. Forged Steel

The material of the crankshaft is directly linked to the engine's intended power and stress levels.

Butler Performance primarily supplies high-quality forged steel and specialized nodular iron stroker cranks from trusted manufacturers who understand the unique bearing and main journal requirements of the Pontiac V8.

3. Key Crankshaft Features and Services

Beyond material and stroke, Butler provides crucial services and features necessary for a reliable, high-performance Pontiac crank:

• Journal Sizing: Pontiac V8s use either 3.00-inch or 3.25-inch main journals. Butler supplies cranks specifically sized for the block being used. They also offer the option of using $2.200$-inch Chevy-sized rod journals, which increases bearing availability and strength.

   

• Rod Stroke Clearance: Butler’s stroker cranks are specifically designed to minimize or eliminate the need for grinding the connecting rod ends and block webbing—a common, time-consuming task when installing non-optimized stroker kits.

• Precision Machining: Every new crankshaft supplied by Butler is machined with features crucial for performance:

  • Chamfered Oil Holes: Smooth oil holes prevent stress risers and aid oil flow.

  • Fillet Radii: The areas where the rod and main journals meet the crank arms are strengthened with large, smooth radii.

• Rotating Assembly Balancing: The most vital service provided by Butler is balancing. Every crankshaft is custom-balanced with the connecting rods and pistons to ensure smooth, vibration-free operation at all RPMs, drastically improving engine longevity and performance.

By choosing a crankshaft supplied by Butler Performance, the enthusiast is guaranteed a product that is not just physically strong, but has been precisely engineered and prepared for the unique torque characteristics of the high-performance Pontiac V8.