I have an ongoing problem with oil pressure. Driving me bananas. Been through the motor 5 times trying to find the problem. Inspected ans changed oil pump 3 times. Bearing clearances are 0.0025 on the rods and mains. Motor is all redone, balanced and blueprinted 468" with 1500 miles. I have a high volume Melling oil pump, Milodon deep pan, Milodon pickup is set 3/8" from bottom of pan. Remote oil filter with 2-qt truck filter, all -10 braided stainless lines. Running 20W50 oil. Hydraulic cam. Starts cold at 60psi idle, hot idle is 40psi. Cruise pressure is 60psi. Up until about 3500-4000RPM, all is well. Then, over 4,000rpm, the pressure drops to 50psi. The strangest thing is every morning I get on the highway and run it through the gears to 5,000rpm. With the car just warmed up, the water temp at 180, and the oil temp 180, when I get the rpms up, I watch my oil pressure and it will go up to about 70psi. But 2 miles down the road, I try blasting it again to 5,000rpm and the oil pressure will act up, dropping to 50psi from cruise 60psi.The gauge has been replaced and acts the same-it's an autometer liquid-filled. I tried adding an extra quart of oil to no avail(the motor holds 8 quarts normally). Went through every oil passage looking for restrictions and found none. Bearing inspections clearly show an oiling problem, I just am out of ideas. Anyone?

With no other changes, remove the remote oil filter set-up and use a single AC PF 35 in the stock location. Don't block off the by-pass valve. Try this first.

Louie Hammel

Why are you running 20-50 oil?I have a Chevy Power book published by GM and they reccomend straight 30 oil for a big block Chev. as long as it's not used at cold temps.Your oil pressures seem kind of high to me,maybe that 50 weight oil doesn't want to flow into those .0025 bearing clearances very easily hence the high pressures.
I run straight 30 in my 454 {summer time only} with no problems.My oil pressures run about 30 at idle and 45 at anything above idle with the engine at 180 degrees.
Just my thoughts,hope this helps.Jerry

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66 El Camino 350 4 speed
68 Nova 454 4speedhttp://community.webshots.com/user/11011954

I might have to give that a try Lou, thanks. It's a real PITA because of the header design/oil pan/frame. That's why I went with a remote. As far as too high a pressure goes, I sure wouldn't want less than 60psi at 6,000rpm. 10psi/1000rpm is absolute minimum for me. With the cam and heads I have, shift point is optimum at 6,000. Thanks guys.

Lou, I gotta tell ya, Thanks! Bit the bullet tonight and pulled the remote setup off and put the stock setup back on. Now have oil pressure that increases with RPM like it should. Thanks again!

Airborn, I'm glad you found the problem. You can still use a remotely mounted filter, you just need a different style. The one you had on there was creating an obvious restriction in a high flow demand situation. The newer ones that seem very popular with the racers use the Fram HP6 filter. I wish one of the aftermarket companies would make a block adapter for this filter. It would probably hit every header made but it sure is big and flows like a fire hose.

Stories with happy endings are always the best ones. (I don't live too far from Hollywood, can ya' tell?)

Louie Hammel