Follow along as we install and test both the Butler Performance standard and Moroso-based Evac Pump Kits. Installation was completed by George Reaves, the owner of the '65 GTO test car at Real Performance Motorsports (RPM) in Lewisville, Texas. Once installation was complete, both systems were dyno tested at RPM and then raced at Redline Raceway in Caddo Mills, Texas.
 The evac pump is then mounted...  The evac pump is then mounted to the aluminum bracket with a 3/8 x 6-inch bolt. Since the drivebelt has yet to be installed, the bolts are hand-tightened, as is the 3/8 x 1-inch bolt and washer that attaches the pump-adjustment bracket to the back of the pump. |  Installation of the drivebelt...  Installation of the drivebelt begins by pushing down the evac pump, allowing maximum clearance to slip the drivebelt over the crankshaft mandrel drive and pump pulley. |  In order to operate correctly,...  In order to operate correctly, the vacuum pump must have a sealed system to draw pressure out of. If so equipped with a PCV valve, the hole in the valley pan will have to be plugged. Since the car wasn't equipped with a PCV valve and had breathers in both valve covers, one breather would have to be capped while the other side was retrofitted to include a bung that would accept an AN-style fitting. |
 Rather than utilizing the...  Rather than utilizing the owner's tall Moroso chrome valve covers, a set of Butler Performance 2 3/4-inch Pontiac billet valve covers were ordered. When combined with a set of 5/16-inch thick valve-cover gaskets, the valve covers will clear aftermarket rocker-arm assemblies. |  To finish off the installation,...  To finish off the installation, the -12 hose length that goes from the pump to the breather was cut to size, and a 45-degree fitting was threaded onto the hose and attached to the breather tank. |  Once complete, the GTO was...  Once complete, the GTO was loaded onto the DynoJet chassis dyno at Real Performance Motorsports where it proceeded to pull a maximum of 5 inches of vacuum at 6,000 rpm. |
Conclusion
It is apparent that both Butler Performance Evac Pump Kits are complete and well designed. Installation can be accomplished in 1-2 hours with the hardest tasks being where to locate the breather tank and cutting the braided hoses to length.
The choice of pumps comes down to the hobbyist's budget and goals. If the primary purpose of the pump is to stop any oil leaks, the standard kit will provide reliable service for years. For enthusiasts looking to gain a bit more horsepower and have the ability to rebuild their own pumps, the Moroso three-vane pump is a great choice.
Other than the ability to stop the pesky oil leaks that plague high-performance engines, the vacuum pumps can and should be used as aids in prolonging piston-ring and cylinder-seal integrity as well as valuable diagnostic equipment.
According to Butler, "By utilizing a dash-mounted vacuum gauge, the enthusiast can carefully monitor the condition of the engine's sealing abilities pass after pass. From a reliability and cost-effectiveness standpoint, both pumps have very good service lives. The GeeTO Tiger's standard evac pump lasted for five years before needing replacement. With replacement pumps retailing for $99 and the Moroso Rebuild Kit running $105, both systems are relatively inexpensive to maintain." For hot street cars and drag racers, a Butler Evac Pump Kit might just be the cure for your pressurized oiling blues.
Dyno Testing
Testing of the '65 GTO was performed at Real Performance Motorsports in Lewisville, Texas. RPM has a Dynojet Model-248C dyno. The car was running on drag slicks, which pulls down the rear-wheel horsepower on a chassis dyno compared to street tires. Due to electrical interference present in the ignition system, rpm was not recorded consistently across all pulls. In addition, torque is not noted as the torque maximums were always dependent on when the engine was floored and the converter was flashed.
Key Engine Parameters: air-inlet temperature (AIT). Vacuum was measured on a sealed system at a valve-cover bung at idle and at 6,000 rpm in Third gear. Maximum horsepower was achieved at 5,400 rpm.
The GTO's big-cube mill put out 340.7 hp in its baseline configuration. Although the firewall and valve covers were clean before the run, the pressure that built up in the engine pushed oil out of the dipstick tube, and it dripped onto the passenger-side header. In addition, the back of the driver-side valve cover was wet, and both breathers had oil residue where they mounted to the valve covers.
 With the standard evac pump...  With the standard evac pump dyno testing complete, the Moroso Evac Pump Kit (PN BPI-EVAC-MOR, $799 retail) is readied for installation. Capable of generating up to 14 inches of vacuum, the pump is also fully rebuildable at home with a Moroso Service Rebuild Kit. |  After removing the standard...  After removing the standard pump and drive pulley, the Moroso Pump Kit installation begins by installing the Moroso-specific pump pulley onto the crankshaft. |  The pump-mounting bracket...  The pump-mounting bracket is positioned onto the passenger-side cylinder head, and a 3/8-inch bolt with a flat washer is hand-threaded into the top mounting hole. |
After cleaning the mess and finishing the installation of the standard Butler Evac Pump Kit, a vacuum gauge was connected to the passenger-side valve-cover fitting. At idle, the car registered 0 inches of vacuum being pulled from the engine-not unexpected since the pump was rotating so slowly. Once the GTO was unleashed, it was evident that the Evac Pump Kit was performing its job. At a maximum rpm of 6,000 in Third gear on the Turbo 400 transmission, the pump pulled 5 inches of vacuum, and the decreased pressure and more effective ring seal allowed horsepower to jump by almost 6. As significant was the fact that the pump completely eliminated the oil leaks that had previously plagued the car on the dyno.