MikeyFIN

Mike told above the same I though about too... the relief valve, you might try a run having it blocked or restricted more, and a new oil pump might also be in order. Be careful still trying as you have still somewhat of an oil pressure saving the engine.

Griff

X2

doctor_ratz

What about the relief valves in the oil pump boss area. On a truck they run two, one under the screw in filter nipple, and one on the surface of the pad. I was told to leave the one out under the nipple, and only put the one in that mounts on the pad. Any issue there ????

ezstriper

make sure pickup has not come loose or off pump...ck galley plugs behind timing gear...if everything checks out recheck bearing clearances as well as correct length lifters...then I would replace pump..

RHM253

Put a mechanical gauge on it to see what you really have for oil pressure, it's a lot easeir than possably tearing down something that doesn't need it.

rexcramer1

He stated in the original post that he already verified the electrical gauges with mechanical ones.

You state that you reused the original cam, maybe there is excessive cam bearing clearance also?

tunertech

540's tend to moves a lot of air inside the crank case as do most strokers. What type of pan and windage control are you using? How big are the oil return holes in the valve train return? Just a few things to look at.

dbkski

iTrader: (1)

Dr. - I will assume this is a typo?

supercat

Any clearance issues (bearings, cam, lifters etc) would not in my opinion only show up above 4000 rpm they would also be giving lower pressures at 3000. The bypass valves on the filter adaptor portion of block would only bypass oil filter and or cooler if open but would not effect oil pressure unless getting way too hot. The relief on the oil pump itself could but again I don't think it would be rpm specific if it was not opening at 60# at 3000 it wouldn't be opening far enough to be below 60# at 4000. It sounds more like starving the oil pump for whatever reason (drain holes, windage, pick up etc) OR the pump is damaged and internals are "wobbling" a bit at the higher rpm and volume. If it were me and I couldn't see anything obvious like windage tray or oil return holes too small, I would start with a new pump.

thumper038

iTrader: (1)

Dont know what size pan you have?
We have run into this condition with more than one customers boat.
HV pump like m77hv and small pan 7/8 qt pan .
Pumping the pan low/dry long run at high rpm.

I like a high pressure std volume in this application.
Jim