Oil pressure drops when I rev

[Pipewrench_Dale]

Looks like its time to restore my old flathead?
For a while Ive noticed that my oil pressure drops about 20-25% when I rev the engine. At idle the pressure is ok - but as soon as I increase the rpm the pressure drops. And as soon as I let it go back to idle the pressure rises back up to normal. There are no noises from the engine and it behaves as it should in all other aspects. Also the pressure never gets down to zero (there is allways some pressure but a bit low when I rev.)
Been trying to figure this out and the only thing Ive come to is that either the oil pressure relief valve is acting up or maybe the bearings are getting worn.

 

The car is a 1940 Desoto business coupe. The Engine has been swapped at some point for a 1954 265 industrial block with a three speed / overdrive transmission. I dont have any idea how many miles it has run.

Daniel
Sweden

 

[Plymouthy Adams]

clean your screen on the pickup in the oil pan.....

[SQ4MN]

For any number of reasons your engine is starving for oil. That is what causes oil pressure to drop when rpm's increase. Could be as simple as a clogged pick up screen, could need a new oil pump but they rarely go bad.