Jon H...Chev 350 oil pres

Your comments: "With only a few exceptions,Chevy not being one of them,10 psi per 1000 rpm is enough for a heavy duty truck or even a race engine. 10 at idle and 30 at 3000 is plenty. A high pressure or high volume pump on a chevy just causes faster distributor gear wear.
..... ..... .."

Respectfully asking: Would you mind sharing with us the origin of your comment concerning 10/1000 and the reason why I should believe you?

If you are a reliable source of information I will be very grateful. I have worried for years about low oil pressure, especially in the GM 350.

I have a Ford and Dodge and the pressure locks right in in the 50ish psi range regardless of idle or 2500 rpm, regardless of hot or cold.

!@#$%^&*()_ Chev is all over the place. Been told they use a high volume, low pressure pump and don't do as others do which is to have a high press, low volume pump and a press relief valve which is what the other 2 must use or they couldn't maintain a steady pressure under all those variables.

Well I know the physical relationship pv=kt and I don't buy the Chevy logic; not yet anyway. Course I haven't done any research on engine lubrication system types to understand why there are the differences mentioned. Guess if I was all that curious I'd have done that. Maybe I will if still concerned after your reply.

Have a Perkins diesel which looses pressure when at operational temp and at idle it goes to around 15 psig at about 800 rpm idle. Don't want to overhaul it as it runs good and the Perk has lots of parts to fool with, but would like to stop worrying about pressure drop off at idle. My other tractors hold at least 30 at idle. (Use the same type 15w-40 or 50 in all engines)

Thanks,

Mark

Mark

Got me to thinking.

Since oil pressure runs in the 10's of psi and the pressure on the bearings of an engine like a 350 is probably in the 100's of psi, it's silly for me to think that the oil pressure is what's holding the metallic surfaces apart.

It has to be the surface tension of the oil; it's ability to stay between the metallic surfaces and not be squished out.

So that leaves (as you said) enough pressure (from the pump) to push the oil through the engine for cooling purposes.

Thinking more about different viscosities; Then it looks like the higher viscosities are necessary at higher temps to keep the oil thicker to keep the pressure up so that an adequate volume of oil can flow (be pushed) thru the engine to keep it cool (and to flush out any combustion crud).

If the oil doesn't flow adequately, the temp of the oil exceeds it's breakdown value (probably at the bearing surfaces), the oil breaks down, quits lubricating (looses it's surface tension characteristics), and you get engine wear.

Makes sense.

Thanks alot.

That says right there that I should expect the oil pressure to vary as a function of rpm's whether or not I understand why.

Thank you very much.

Mark

I liked the Motor's engine specs.

Enjoyed the yak.

Mark