Butler Performance’s offering begins life as an M-54F unit that is completely disassembled and re-machined. During the process, a lubrication groove is cut into the driveshaft bore and the driveshaft is micro-polished. The pump-gear pedestal pads are diamond-lapped and also feature a lubrication groove. The idler gear bore is honed and an oil weep hole is added to prevent oil cavitation—a condition where trapped air pockets collapse, causing irregular shock loads that can prematurely fatigue components.

Certain Pontiac oil pumps were equipped with a thick, cast bottom plate. “We’ve seen some of the thinner, stamped plates that are common on today’s pump flex with pressure as low as 20 psi, and that can have negative effects,” says Butler. “We use an extra-thick, cast bottom plate on our Pro-Series pump. It is diamond-lapped to improve sealing, and contains machined grooves to prevent cavitation and improve lubrication between the gear and plate.”

The bypass-valve ball and sealing surface of its Pro-Series oil pump are machined and blueprinted. “The bypass spring is tested to ensure consistency, and pressure is set to 75-80 psi at the gauge—though depending upon bearing clearance, it could be higher within the engine. We can shim the pressure relief spring to increase pressure slightly, or install a 60-psi assembly to reduce pressure, depending upon the engine’s needs. The finished pump is completely tested and includes a detailed flow chart,” Butler adds.

Along with an enlarged discharge hole, the total effect of Butler’s internal modifications also improves oil flow of the Pro-Series pump. “Maximum oil flow on a stock-type 60- or 80-psi pump with a stock pickup screen is usually 12-13 gallons per minute (gpm), and cavitation within the pump makes that output rather inconsistent,” says Butler. “Our modifications significantly reduce cavitation and increase maximum flow to 18-19 gpm, when combined with a good aftermarket pickup.”

Butler thinks that the Melling Select pump is adequate for street engines that operate at speeds less than 6,000 rpm. “We recommend our Pro-Series oil pump for almost any application, but highly recommended it for engines that will see more than 6,000 rpm or generate more than 550-600 hp. We’ve seen engines making more than 1,500 hp operate suitably using a standard Pontiac pump, but we begin suggesting other gerotor-type or billet dry-sump pumps when engines exceed 1,200-1500 hp.”

Oil Pressure Requirements

A common question from many Pontiac hobbyists is about oil pressure and just how much is required. “We generally feel at least 10 psi of oil pressure for every 1,000 rpm is the minimum requirement for reliable operation,” says Butler. “We recommend 20W-50 oil for our high-performance engines, and like to see hot-idle oil pressure between 30 and 40 psi. Pressure as low as 15-20 psi doesn’t necessarily present a risk as long as it isn’t a sign of other problems, but the amount of time it takes pressure to climb to 60 psi or more can put the bearings at risk on a quick-revving, high-performance engine.”

Butler says that since an engine with smaller-diameter main journals (3-inch) and shorter-stroke crankshafts (4.21-inch or less) is generally less stressful on the bearings, a 60-psi pump may provide adequate lubrication in a modified engine, but an 80-psi pump is a better choice. He says any performance engine with 3.25-inch-diameter main journals and/or a stroker length greater than 4.21 inches should use an 80-psi pump. “The greater oil pressure associated with the 80-psi pump improves the strength of the oil film, and better protects the bearings in large journal and/or long-stroke applications,” he adds.

Common hobbyist concerns when using an 80-psi oil pump in a street engine include excessive parasitic loss, bearing wash, and premature distributor and/or cam gear wear.

“We’ve never seen a noticeable performance loss from the added load,” says Butler. “Racers will sometimes run a 60-psi pump to reduce parasitic drag and free up a few horsepower. While that’s acceptable in a dedicated race engine that’s frequently torn down, it’s certainly not something we recommend for all engines.”