455 Blocks (462-503 cu. In.)

Rotating Assemblies & Stroker Kits - 455 Blocks (462-503 cu. In.)

The Pontiac 455 V8: The Ultimate Torque Monster

The Pontiac 455 cubic inch V8 holds a unique and revered place in muscle car history. Introduced in 1970, it was the largest engine produced by the Pontiac division, serving as the power plant for iconic models like the GTO, Firebird Trans Am, and high-end full-size cruisers. Unlike other General Motors divisions that had dedicated "big block" and "small block" engine families, Pontiac simply continued to grow its singular V8 design, resulting in an engine renowned not just for raw horsepower, but for its colossal torque production.

Select a Sub-Category

View  
Rotating Assemblies & Stroker Kits - 455 Blocks (462-503 cu. In.) - 455 Stroker Rotating Assemblies
455 Stroker Rotating Assemblies
Designed, built, tested and proven with years of experience and knowledge in the Pontiac high performance industry. Our assemblies are put together with parts selected and used specifically in...More Details »

More About 455 Blocks (462-503 cu. In.)

 

The "Big Journal" Foundation

The strength of the Pontiac 455 lies in its architecture. With a stock bore of 4.151 inches and a long stroke of 4.210 inches, the factory engine was built for moving mass. Crucially, the 455 belongs to Pontiac’s “big journal” family, featuring 3.25-inch diameter main bearings, which offers a robust foundation compared to the 3.00-inch mains found on 400 blocks.

For performance builders, the stock 455 block remains a durable platform. Pontiac experts confirm that most factory blocks are suitable for performance builds, capable of handling cylinder bores up to .060-inch over. While many 455s came standard with 2-bolt main caps, the high-performance versions, such as the legendary 455 H.O. and 455 Super Duty (SD) engines, often featured the more desirable 4-bolt main caps, signifying their racing heritage. The standard 455 blocks are considered strong enough for street applications approaching 600 horsepower before needing extreme modifications.

The Quest for Displacement: Building a 500+ Cubic Inch Pontiac

While the factory 455 is powerful, the modern performance enthusiast often uses the robust block as a starting point for even larger displacement through stroker kits. Since the Pontiac V8 block shares common external dimensions, its internals can be modified to create massive cubic inches.

Companies like Butler Performance specialize in maximizing the 455 block’s displacement by increasing the stroke past the factory 4.210-inch mark:

  • 4.250-inch stroke: Converts the 455 into a 467–474 cubic inch engine.
  • 4.500-inch stroke: Pushes displacement up to a massive 494–503 cubic inches.

By combining these longer strokes with modern components like forged pistons and H-beam connecting rods, builders can create streetable engines capable of churning out impressive figures. Performance combinations utilizing the 455 block often yield:

  • Pump Gas Street Performance: 600–650+ HP and over 625 ft-lbs. of torque on pump gas (91–92 octane). This power is achieved with aftermarket aluminum cylinder heads (such as Edelbrock units) and hydraulic roller camshafts, which significantly improve airflow and efficiency.

For those pursuing extreme track performance exceeding 850 horsepower, Butler Performance also utilizes specialty IAII aftermarket blocks (available in cast iron or aluminum) that are reinforced in critical areas for maximum durability, although the factory 455 block remains the heart of the most popular street-strip builds.

The Pontiac 455 V8 stands as the pinnacle of Pontiac's unique V8 lineage. Its factory design, particularly its large main journal and generous stroke, make it an exceptional candidate for modern performance upgrades, resulting in engines that deliver brutal torque and exhilarating speed.