[Steve C.]

This is a good read:


https://www.hotrod.com/articles/hppp...-observations/

"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.”

He continues: “We’ve run as much as 100-psi on some engines and have never experienced any bearing wash issues. Excessive distributor or cam gear wear can result, particularly with a bronze gear, but we consider positive cam-gear oiling a must when running a roller camshaft, and we found that it significantly improves distributor gear life.”

One area that many hobbyists overlook when selecting an oil pump for a particular engine is camshaft type. “Some of the aggressive hydraulic- roller-lobe profiles available today and the high-pressure valvesprings required to effectively maintain valvetrain stability can cause the roller lifter’s hydraulic internals to bleed down too quickly, and that can create a performance loss. In these instances, additional pressure (75 psi or more) is required to keep the hydraulic lifters working properly,” states Butler."



.