The Stovebolt Site Forums The Shop Area Engine Shop 1962 chevy 261 idling oil pressure.

just curious as to what the pressure should be when im idling. if i have a 30lb gauge, is 15lb idling ok? i think its usually higher when its cold and gets lower as it heats up and the oil gets thinner.Just wondering.
Thanks,
Dan

Most "idiot light" switches turn on at 7 PSI, so anything above that is probably OK. As long as the bearing furthest away from the oil pump gets an adequate flow of lube, the pressure is irrelevant. I'm not terribly upset with anything above 15 PSI at a hot idle. Cold engines will normally run 30-40 PSI at idle, sometimes more. The reason oil pressure builds up at all indicates the pump is delivering more oil than the bearings can leak away. If the bearings, lifters, etc. are consuming exactly what the pump delivers, no more or less, the pressure would be zero, yet everything would get lubed. Oil pressure of any amount is an assurance that there's more oil flowing than necessary, as long as that pressure finds its way to the far end of the oil system.
Jerry

First, I agree with Jerry - you are probably all right.

However, a reading of 15 psi oil pressure from a 261 is low. The pressure relief setting (a spring, I think) for this engine in between 30-45 psi.

I ran my "high-pressure" 235 at 5 psi for a long time but it finally got so low at idle that I would get a 0 psi reading.

If the engine drives OK, just keep an eye on the oil pressure. Also, consider switching to a higher viscosity oil (I used 20W50 with my worn out 235).

The pressure relief setting (a spring, I think) for this engine in between 30-45 psi.

Has nothing to do with the idle pressure. If I put a marble in the relief valve, I can make the relief setting 500 lbs. - and the idle pressure will not change.

I have a 261 in my 46 with the original 30# gauge, it's pegged all the time and the gauge works. I'd check your pressure with another gauge before you do anything major, but I thinks it's to low.

remember, im talking about idling, when i just touch the gas it pegs past 30.just when i stop and it comes to a really slow idle, it drops to about 15psi.i think i should be fine as long as it doesnt go lower than that.
Dan

How about raising the idle speed just a little? I'm pretty sure you're dealing with slightly loose rod and/or main bearings that are dropping the pressure at slow idle when the oil pump output volume is minimum. The pressure relief valve simply prevents overpressure when the pump speed allows it to produce much more volume than the engine needs for lubrication.
Jerry