Holley Carburetors

1. The Street Avenger: Streetability and Simplicity

For the majority of street-driven Pontiac V8s, the Holley Street Avenger series is an excellent starting point. These carburetors are designed for out-of-the-box performance and are specifically calibrated for street use, offering a blend of easy installation and reliable daily driving.

• Vacuum Secondaries: The Street Avenger models utilize vacuum-actuated secondaries. This means the engine itself dictates when the larger secondary throttle plates open, ensuring that the carburetor doesn't provide more airflow than the engine can handle at low RPMs. This results in excellent street manners, better low-end throttle response, and improved fuel economy compared to mechanical secondaries.

   
   

• Easy Setup: They often come with a factory-preset electric choke for quick cold starts and feature a simple calibration that works well on a wide range of mild-to-moderate Pontiac engines, such as a stock or mildly cammed 400ci or 455ci.

   

• Sizing: Common sizes like the 670 CFM and 770 CFM are ideal for most street-strip Pontiac applications running dual-plane or single-plane intake manifolds.

2. The Double Pumper: Race-Ready Street Performance

When a Pontiac V8 is destined for frequent track use or demands instant off-the-line power, the Holley Double Pumper is the iconic choice. These carburetors are defined by their mechanical secondaries and dual accelerator pumps.

• Mechanical Secondaries: Unlike the vacuum secondaries, the secondaries open immediately when the throttle is pushed past approximately 50 percent. This provides an instant, massive rush of airflow and power—perfect for light vehicles, low gearing, and manual transmissions or high stall speed automatic transmissions.

• Dual Accelerator Pumps: One pump handles the fuel shot for the primary bores, and the second handles the secondaries. This ensures there are no fuel "flat spots" when the secondaries snap open.

• Application: Ideal for dedicated street/strip machines where maximum acceleration and torque are prioritized over daily efficiency. Butler Performance offers these in sizes like 750 CFM and 850 CFM, depending on the engine's cubic displacement and horsepower target.

   

3. The Max Effort Series: HP, Ultra XP, and Dominator

For extreme high-performance and race-only Pontiac applications, Butler Performance carries the specialized Holley lines:

• HP (High Performance): This is Holley's original race-ready carburetor. They are performance-calibrated and feature screw-in air bleeds for precision tuning, along with contoured venturi inlets for balanced airflow. The 950 CFM HP is a common size for large-displacement, high-RPM Pontiac race engines.

   

• Ultra XP: This is the ultimate evolution of the 4150-style square-bore carburetor. Built with aluminum construction (saving significant weight) and featuring billet metering blocks and base plates, the Ultra XP line offers maximum durability and tuning adjustability, including high-capacity bowls for severe racing conditions.

   

• Dominator (4500 Series): For massive, high-cubic-inch Pontiac engines (often over 500ci) running high-rise race intake manifolds, the four-corner Dominator is the benchmark. With airflows exceeding 1000 CFM, the Dominator is strictly reserved for maximum horsepower race applications.

   

Whether an enthusiast requires the daily ease of a Street Avenger or the all-out race tuning of an Ultra XP, Butler Performance utilizes Holley's diverse and proven lineup to provide the precise fueling needs for any Pontiac V8 build.