Evac Pump Kits & Accessories

The Science: Why Vacuum Adds Power

Every engine, especially one built for performance, experiences blow-by—combustion gases escaping past the piston rings into the crankcase.² This rapidly builds pressure in the lifter valley and oil pan. This pressure has several negative effects:

1. Reduced Ring Seal: Crankcase pressure works against the piston rings, pushing them slightly away from the cylinder walls.³ This worsens the seal, leading to more blow-by and power loss.

2. Increased Oil Leaks: The pressure forces oil mist out of every possible seal (gaskets, dipstick tube, etc.).⁵

3. Windage and Aeration: High-pressure air surrounding the rotating assembly increases windage (resistance), which robs horsepower.

An Evac Pump (Vacuum Pump) is a belt-driven mechanical pump that actively sucks air and oil vapor out of the crankcase, creating a negative pressure or vacuum (typically 12-15in).

The Resulting Benefits:

• Better Ring Seal: The vacuum pulls the rings tighter against the cylinder walls, improving combustion efficiency.⁶ This effect alone can yield noticeable horsepower gains (often 10-20hp).

• Reduced Oil Consumption: By lowering pressure, oil is less likely to be forced past the valve guides and seals.

• Cleaner Engine: Reduced contamination and fewer leaks mean a cleaner engine and engine bay.

    

The Butler Complete Evac Pump Kit

Butler Performance makes the transition to a race-style vacuum system seamless by bundling all necessary Pontiac-specific components, eliminating the complexity of sourcing individual parts.

• Premium Vacuum Pump: Kits feature high-efficiency, billet aluminum vane pumps from trusted race suppliers like GZ Motorsports or Moroso (available in 3 and 4 vane options for different vacuum levels).¹⁰ These billet pumps are durable and consistent, a massive upgrade over header-mounted evacuation systems. 

• Crank Drive Mandrel System: This is the key to driving the pump. Butler includes a specialized Billet Pontiac 4-Bolt Crank Drive Mandrel Kit that bolts to the harmonic balancer and includes the necessary drive pulley and custom-fit spacers for perfect alignment.¹¹

• Plumbing and Fittings: All kits include high-quality, pre-sized braided hose and AN fittings (often -10 and -12AN depending on the pump) to run cleanly from the pump to the valve cover or valley pan.¹⁴

• Oil Separator/Catch Can: The air sucked out of the crankcase contains oil vapor.¹⁵ The kit includes a Breather/Catch Can to capture the oil mist, preventing it from being released into the atmosphere or damaging the pump.

• Adjustable Vacuum Relief Valve: Butler's kits now include a billet adjustable vacuum relief valve.¹⁶ This is a critical component that allows the builder to precisely set and limit the maximum crankcase vacuum to optimize performance for any given engine combination.

    

Customization and Application

Butler offers different options based on the builder's preference and application:

By utilizing a Butler Performance Complete Evac Pump Kit, the Pontiac builder installs a tested and proven system that ensures maximum efficiency, power output, and protection for their high-dollar performance engine.