68 C3 oil pressure

[Ed Driscoll]

Hi Guys,
Whats the normal operating oil pressure for a 68 327/300?
Thanx
Ed

[Joe L.]

Re: 68 C3 oil pressure

Ed------

30 to 45 PSI. However, Corvette oil gauges are not necessarily accurate with respect to PSI readings. They are usually accurate in a relative sense, but not necessarily accurate in an absolute sense. To determine an accurate PSI reading for your car, I recommend temporarily installing an accurate test gauge in parrallel with the car's gauge. Then, you can "calibrate" the car's gauge and understand what the real PSI is at the various "hash marks" on the car gauge.

[Joe L.]

Addendum

Ed----

By "normal operating pressure", I'm assuming that you mean at cruise of 2,500 RPM, or so.

[Ed Driscoll]

Re: Addendum

Idle (around 750 rpm) and 2500 rpm would be great.
thanx Joe
Ed

[Ed Driscoll]

Re: 68 C3 oil pressure

so if my gauge was reading 50-55 @ idle, is this cause for concern. the engine sounds fine, no shake, warmed down to a smooth idle very quickly. I haven't hit the highway yet, so I'm not able to load the engine and drive at 2500 rev's. I did just replace the dash/cluster/console/wiring, so everything has been apart and re installed, including the oil pressure gauge. what would cause a high oil pressure reading?
thanx
ed

[Joe L.]

Re: 68 C3 oil pressure

Ed-----

50-55 lbs at idle is WAY too high, IF the reading is accurate. Even a "high pressure" oil pump should not generate that high of an idle reading (assuming that the engine is warmed up and no more than 10W-40 oil is being used).

The engine at operating temperature readings should be about 15-20 PSI at idle and about 30-45 PSI at 2,500 RPM cruise

[Ed Driscoll]

Re: 68 C3 oil pressure

castrol 10-40w. what might cause this high of a reading?

[Joe L.]

Re: 68 C3 oil pressure

Ed-----

Most of the things that could cause this would involve going back into the engine. So, I would want to know if the reading is accurate before moving onto the next step in a possible correction strategy.

[Steve Miller]

Re: Addendum

Ed

The engine builder for our Busch motors has warned us that the race motor oil pressure should never exceed 10 lbs per 1000 rpm within our normal operating range. Just a guide line. We run Amsoil synthetic and have never had a problem.

Steve

[Patrick H.]

Re: 68 C3 oil pressure

Joe,

I'll disagree, up to a point.

First, Ed should verify that his gauge is correct.

Second, he hasn't even taken his car on the road yet. Odds are that the motor is cold. With 10W-40 "diesel oil" (as I refer to it after Duke's lectures) I often hit 50+ psi on COLD start. By the time I'm a few miles down the road I'm often at 30-35 PSI INDICATED. It will go just under 30 PSI INDICATED at idle when warm. So, since Ed hasn't moved the car yet, I wouldn't worry.

You want lower indicated pressure? Switch you oil. I run about 5 psi lower with mineral based 5W-30, and a switch to 5W-30 synthetic will drop me 10 PSI from what I'm running now. Absolutely. Positively.

Patrick