AkrHack

I bought a '71 with the 270HP/350 engine last week. When inspecting it prior to the purchase, the oil pressure gauge was not working. Since, it did not exhibit any of the signs of low oil pressure like lifter clatter or main bearing knock, the non-functional gauge did not dissuade me from buying the car.

Fast forward to this week now that the car is mine. One of the first things I'm doing is to address the non-functional oil pressure gauge. While diagnosing the problem as being the gauge itself, an external oil pressure gauge was hooked up the oil pump and the oil pressure read 30psi with a hot engine at 2000 RPM. Is this 30psi oil pressure a reason for concern? The car has fresh 10W-30 motor oil in it.

I'd appreciate opinions of the other forum members.

Bromleys Corvettes

Whats more important is what it reads at a idle. That kinda tells you whats up. Running a thicker wt oil like straight 40 will help some and plugging the presser relief on the oil filter adapter. Also does the presser jump up when you bring up the rpm from idle. Like it should jump up real fast if not its a bad sign. Like bearings clearances and pump tired. The cool thing about the vettes is you can drop the pan and change the pump with out pulling the engine. If needed

Bromleys Corvettes

Most of the vettes I work on have 30 to 40 at idle and jump up to 60 or 70 when you hit the gas a little.

PeteZO6

The rule of thumb is 10 pounds of pressure for every 1,000 rpm. Mid your engine meets that no worries. Yours doesn't, you need to figure out why. Worn main and rod bearings are probably the most common reason for low oil pressure.
Before digging into the engine, determine if the gauge is accurate. You can buy an inexpensive oil,pressure gauge and run the line from just above the oil filter on the side of the block. If the pressure is good on the new gauge, you can fix the dash gauge.
Information is power

Pete

Solid LT1

Why the modern era 10/30 WT? In the good old days straight 30WT I would try a 10/40 or 20/50 WT. oil is cheap compared to an engine rebuild. 30psi hot is OK if it's cold start up pressure, I'm share it will drop lower at temperature that would start to concern me.

7T1vette

30 psi at 2000 rpm is fine. At idle, if you have a stock GM pump, that pressure could drop to as low as 5 psi; but 10-15 at idle would be more normal. If you rev it to 3000 rpm it should be in the 40-50 psi range. If the oil pressure doesn't increase with increasing rpm, then there is a problem with the pump OR you have some bearings that are getting pretty worn.

Having EXCESS of oil pressure throughout the engine's rpm range is totally unnecessary for a street-driven vehicle. And throwing higher weight oil in your engine...just to see the oil pressure go up....is just looney.

ajrothm

15-20 hot oil pressure at idle is fine, especially for 30 wt. I'd probably put some 10w40 in it just because your bearing clearances are probably on the loose side a bit. I bet you pick up 7-10 psi hot oil pressure at idle with 10w40.

I wouldn't worry about it.