Short Blocks (Assembled and Unassembled Kits)

The Power Foundation: Pontiac Short Blocks from Butler Performance

For the Pontiac enthusiast who possesses the expertise or wishes to handle the cylinder heads, valvetrain, and induction system themselves, Butler Performance offers a critical solution: Pontiac Short Blocks.¹ These assemblies provide a meticulously blueprinted, fully machined, and balanced foundation—the engine block and rotating assembly—that is ready for the builder to finish.²

Available as both fully assembled units and complete unassembled kits, Butler Short Blocks save the builder considerable time, expense, and risk associated with finding, machining, and balancing the core components, while still allowing for complete personalization of the top end.

What is a Butler Short Block?

A Butler Short Block consists of the core components of the engine:

1. Engine Block: A cleaned, machined, and blueprinted Pontiac block (e.g., 400, 455, or aftermarket IA II block).

2. Crankshaft: High-quality nodular iron or forged steel crank, often part of a stroker kit

3. Connecting Rods: Forged I-beam or H-beam rods.⁴

4. Pistons and Rings: Forged pistons matched to the compression ratio and bore size, installed with high-quality rings.

These components represent the majority of the complex and expensive machine work required in a high-performance build.

Assembled Short Blocks: Ready for the Top End

The assembled short block is Butler Performance's most popular offering in this category. It delivers a foundation that has been completely finished and assembled by their expert engine builders.⁵

• Precision Assembly: The rotating assembly (crank, rods, pistons) is fully installed into the block, complete with the main bearings, rod bearings, and piston rings.

• Blueprinted Clearances: All critical tolerances—main and rod bearing clearances, piston-to-wall clearance, ring end gaps, and deck height—are meticulously set to Butler’s high-performance specifications.

• Ready-to-Go: The engine arrives ready for the builder to install the oil pump, timing set, camshaft, cylinder heads, and intake. This saves the builder the hassle and expense of final measuring, cleaning, and assembly.

• Durability and Displacement: These units are frequently built using Butler’s proprietary stroker kits, transforming stock blocks into massive displacement engines like the 461/468ci (from a 400 block) or the 505/535ci (from a 455 block), built to handle 600hp or more.

Unassembled Short Block Kits: The DIY Approach

For the experienced engine builder or machine shop, the unassembled short block kit provides all the core parts necessary for a build but leaves the final assembly and measuring in the customer's hands.

• Complete Parts Kit: This package includes a fully machined, prepped block (honed, decked, line bored) and all the necessary components (crankshaft, rods, pistons, rings, bearings).⁶

   

   

• Cost-Effective: This option is slightly more cost-effective as it bypasses Butler's final assembly time.

• Flexibility: It allows the builder to use their preferred final assembly lubricants, measuring tools, and internal quality control checks.

• Risk Mitigation: The customer still receives the highest quality, dyno-proven Butler stroker components and a block that has passed Butler's rigorous machining standards, greatly reducing the risk of component failure.

The Butler Promise: Balanced and Blueprinting

Regardless of whether the kit is assembled or unassembled, every Butler Short Block benefits from two crucial processes:

1. Rotating Assembly Balancing: All components—crankshaft, rods, pistons, and pins—are internally or externally balanced to less than half a gram. This ensures smooth, vibration-free operation at high RPMs, which is critical for engine longevity.

2. Block Blueprinting: The block is thoroughly inspected and machined to ensure that all critical surfaces and dimensions (deck flatness, bore alignment, and main bore sizing) are perfect, eliminating the dimensional inconsistencies often found in vintage Pontiac castings.

By providing these foundational assemblies, Butler Performance empowers enthusiasts to create reliable, high-horsepower Pontiac V8s tailored exactly to their preferred valvetrain and induction systems.