Re: Regulating oil pressure.

Posted by Tim Cole On 2016/10/14 17:11:09

When that car was built they didn't make multigrade oils. The regulator would dump excess pressure when cold and as the oil warmed and thinned less pressure would be bypassed. So the Packard specification for oil pressure is for a fully warm engine running on the road with oil temperature up near 160F. The rule of thumb for minimum oil pressure is 10 psi per 1000 rpm so for a Packard running 50 mph 25 psi is the absolute minimum, but that number two rod is the one that likes to go into orbit. Brand new modern cars do lose idle oil pressure as the enigines get hot but hold pressure on the road.

The rear cam bearing is a culprit as is the oil pump. They all need to be reconditioned but costs and sources are a problem. EGGE Machine was doing the eight cylinder pumps.

When they were new Packards had great oil pressure which is why the old timers were always trying crank it up. But if the pump is worn it can't keep up.

Oh, and if anyone doubts the oil pressure on those cars when new I have a picture from 1930 around here somewhere. I think it shows MPH zero, no charging - so idling, and near 40 psi, with the temperature near the N in range.