Hi I have a 1986 camaro iroc z with a 305 tpi engine and a 700r4 trans I've been having issues with oil pressure when sitting for a while oil pressure is like 45 to 50 psi the more I drive it the lower the gauge gets to the point it's in the red on the gauge I hooked a mechanical up to it and it reads 18 to 20 psi at its lowest that I saw. Is that normal for oil on this car. What could cause it I've heard cam bearings are famous for this problem and if it is those and I just take the motor out and do just the cam bearings alone any help is appreciated and also the sending unit is new

 

Sometimes old Permatex can come loose and partially clog the gauge sending unit.
It makes people panic thinking that they have little or no oil pressure.
Check for this first.

 

The mechanical I hooked up in its place said 20npsi isn't that low for this engine and if it is clogged how can I clean it

 

How many miles are on it?

Mine has about 40+ lbs. cold
and 20 lbs. hot.
all at idle.


But it does have 180,000 miles.
So low oil pressure is expected.

 

What oil are you running, how many miles? If you have 20 PSI at idle with a hot engine I think you are ok. 20 lbs is on the lower side but safe. If you mean you only have 20PSI while crusing, that's a different story

 

Which I assume would be, at idle, hot?

That's extremely "normal": pretty much the textbook description of what a stock SBC gets when equipped with the stock "high pressure" oil pump (which all of our cars came with).

Sounds like your car has about the same as his.

Doesn't sound to me like you have an oil pressure problem; rather, you have a gauge problem.

I'd suggest replacing the sending unit. "New" or not.

When in doubt, swap it out.

Repeat the above until memorized.

I've heard the Earth is flat and the universe is 6000 years old too.

 

I run 10w40 oil and as far as miles on the engine mileage it was swapped into the car so not sure but I've recently been inside when I did my intake and stuff and the motor is as clean as can be inside its spotless.and I went out and got a new sender and it seemed to fix it now it seems to agree with the mechanical gauge and no longer goes on the red

 

 

There's some kind of theoretical measuring stick I've been told that 10 pounds of pressure for every 1000 rpms is enough. Is this accurate??

 

That's a 60's old school general rule for racing (sustained high rpm).
Your pressures are fine.