Pontiac Cast Iron Cylinder Heads and Services

Respecting Tradition: Pontiac Cast Iron Cylinder Heads and Services from Butler Performance

While modern aluminum cylinder heads offer superior flow and weight savings, the original cast iron Pontiac heads remain central to the classic car hobby. For many builders, a restoration or a mild-to-moderate performance street engine demands the authentic look and feel of the original factory heads.

Butler Performance, renowned for its deep expertise in all things Pontiac, recognizes the value of these original castings. They offer a comprehensive suite of services and products that upgrade and restore cast iron heads—such as the coveted $6\text{X}$ and $16$ castings—turning decades-old parts into reliable, high-performance components.

The Case for Cast Iron

For specific applications, properly prepared cast iron heads are still a great choice:

1. Period Correctness: The definitive choice for concourse restorations or classic street cruisers where the engine bay must maintain a factory look.

2. Budget Street Builds: For street engines targeting power levels below $500\text{hp}$, a well-prepped set of cast iron heads is a cost-effective solution.

3. Low Compression Goals: Later casting numbers (like the $6\text{X}$) offered larger combustion chambers, making it easier to achieve pump-gas-friendly compression ratios (around $9.0\text{:1}$ to $9.5\text{:1}$) on large-cubic-inch engines.

The "Butler Built" Cast Iron Head Service

Butler Performance offers a full restoration and performance blueprinting service for both D-Port and Round Port cast iron heads, available either on customer-supplied cores or on cores supplied by Butler.

• Complete Restoration: Every head undergoes a multi-step cleaning process, including disassembly, chemical cleaning, and Magnafluxing to check for cracks—a crucial step for older iron castings.

   

• Precision Valve Job: A competition-grade, multi-angle valve job is performed on a precision Serdi machine, ensuring perfect valve seating and flow.

   

• Performance Valvetrain: New components are installed to modernize the heads:

  • Ferrea Stainless Steel Valves: High-quality, severe-duty valves replace original components.

     

  • Bronze Guides: Full bronze guides (not just liners) are installed to ensure longevity and superior valve stem sealing.

     

  • Performance Springs: Matched valve springs, retainers, and locks are selected to handle the lift of popular performance camshafts.

     

These Butler Built cast iron heads (available as stock rebuilds or custom-ported units) arrive complete and ready to bolt onto the block, retaining the classic look with modern internal reliability.

Critical Cast Iron Upgrades and Services

Due to the inherent design and age of the original iron castings, specific machining services are necessary to ensure they hold up under performance use. Butler Performance offers these upgrades individually:

• Cast Iron Head Porting Service: Butler is one of the premier shops for porting Pontiac cast iron heads. This service takes customer-supplied D-Port or Round Port heads and extensively ports and polishes the runners to increase airflow, helping the classic heads support higher horsepower figures (up to the $550\text{hp}$ range when fully optimized).

• Rocker Stud Conversion: Factory cast iron heads often came with weak, press-in rocker arm studs. Butler offers a critical upgrade service to convert these to $7/16$ inch screw-in rocker studs. This is mandatory for any performance cam with high spring pressures, preventing stud failure or pull-out.

   
   

• Milling: Custom milling of the deck surface is available to reduce the combustion chamber volume (CC) and fine-tune the engine’s compression ratio, ensuring optimal performance with available pump fuel.

   

Whether a builder needs a period-correct, leak-free factory restoration or a set of fully ported heads for a traditional street machine, Butler Performance provides the precision machining and components necessary to make any Pontiac cast iron head a reliable and powerful part of the engine package.