guys i need help.not 100 percent on a oil pressure problem ,not sure it is a problem so im throwin out the question .i have a 1969 400 motor slightly upgraded components engine wise also a mondello intake, 725 demon crb and msd ignition 4spd manual trans.i installed a oil pressure gauge which at idle is showing about 16 to 18 lbs of pressure not sure if its good or bad can anyone help ? at 1500 to 2500 rpm it responds to almost 40lbs is this normal ? any suggestion if i have not given enough info let me know i will provide all i can .and thanks in advance for the help....

 

That is quite normal, and perfectly acceptable for a stock engine.
However if you intend to get heavy footed very often you might consider upgrading the oil pump, and possibly lifting the motor out and having a look at the bottom end.
But if you just want to cruise and occasionally give it some beans then unless you have other symptoms like oil pressure very slow to come up then stop worrying and enjoy driving your car.

Roger.

 

That is a wee bit low, however, I think the old 10 psi per 1000 RPM minimum still holds for a stock engine that isn't expected to see severe use.

Is your gauge mechanical or electric? Mechanical gauges are much more accurate.

 

Completely normal.

- Eric

 

Being a gear pump connected by gearing to the crank, the oil pump output is proportional to engine speed.

The oil flow thru the engine is not so variable with engine speed- it is more like a constant demand.

Therefore, at low RPM's, the oil pump output may not be enough flow to generate the full pressure at which the bypass will open to control the max pressure.

As long as you have over 7 psi at idle [factory lite switch activation pressure] and whatever your bypass spring induces above 1500 or so RPM, it's working correctly.

 

My 76 350 olds has about 5-7 pounds in gear idling at 550 rpm when warmed up completely (at least half an hour at highway speed driving). 35-40psi while cruising. It's been this way for 60k miles + and almost 10 years. Plus at has never been rebuilt as far as I can tell and probably has 2-300k miles on it. I drive the **** out of it at times and never had any issues or noises. No oil usage either.