loosing oil pressure

[oldcarnut]

I have a problem with my 65' 427 top oiler that doesn't make sense. When started it ha 50 psi oil pressure, when you increace the RPM's the pressure drops to 30 PSI. I am checking it with a mechanical guage . Anybody seen this. I'd appreciate any help allot. By the way it has a neww Melling pump and pickup.

[CSX 4027]

Need more info.
How fresh is the motor?
50 at idle start up cold?
What about idle at hot?
What kind and weight of oil?
Have you checked lines for blockage or severe bend/kink?
Have you checked gauge?
What do the plugs look like?
Have you checked oil pump drive?

[Michael C Henry]

Sounds like the oilpump is starving .Has the pan been bent up into the pickup?Could anything have been in the pan and ended up blocking the pickup. The pan may be too close to the pickup causing it to starve for oil. You can check by removing the pan ,putting a peice of clay on the pickup and temporarily install the oilpan.Remove the pan and see how much the clay was pinched,

[FFR428]

Is the oil pump a std, high volume or hIgh pressure? It's also possible there may be some junk in the pump or tolerances are way out. What kind of oil pan and pickup are you using? As stated you might be starving the pan if you swapped out a std pump for a HV type. G.

[PatBuckley]

Try (temporarily) putting another 3 quarts of oil in it and see what it does. If the pressure then stays up I would say it is a starving issue.

[Clois Harlan]

How old is the engine needs to be answered first. But, there is one thing that I am very familiar with is rod and main bearing wear that will cause a loss of oil pressure and a subsequent engine failure.

Bearings are cheap and easy to replace and can prolong the life of most engines. If your engine has been periodically thrashed at a race track or has had oil changes neglected your bearing wear could be substantial. Just a thought and a good winter maintenance procedure.

Clois

[oldcarnut]

The motor is fesh,4-5hours run time, test guage is known to be good. Chrome stock style oil pan that I took off first suspecting the screen to be too close but it has 1/2" clearance. Cold idle is 50 psi, cold rpm increase to 2000 rpm and pressure drops to 25-30 psi, hot running idle 25-30 psi drops to 10-15 psi when rpm raised to 2000 rpm.

[FFR428]

What kind of melling pump??? If you switched form a stock melling to a HV (high volume) and running the stock style pan that's the problem or part of it. It will suck the pan dry and pressure will drop quickly. JMO, G.