Is my oil pressure excessive?

[cockerstar]

Hey guys,

 

Today I tried to help my buddy break in the 327 he built for his 65 Chevy pickup.

 

At a high (800-1000rpms) cold idle we're seeing 75psi on a mechanical gauge.

At around 2000rpms we're seeing around 90psi and it is leaking oil from the rear main and the intake manifold gasket at the front of the valley. We haven't taken it much higher than this.

 

I've read that 20psi at a hot idle is healthy with a general rule of thumb being an additional 10psi of pressure for every 1k rpms, for a max of 80psi at 7000 rpms.

 

He has a high volume oil pump (still checking on brand) and is running 10W30 conventional oil with a comp cams break in additive. The dipstick shows an appropriate oil level.

 

This all seems quite excessive to me, and we're getting a lot of smoke out of the valve cover breathers (blowby).

 

Any ideas on what could be causing this, and if we're looking at doing any damage by leaving it?

 

A failed pressure bypass valve would yield higher pressures, right?

 

 

Thanks,

Ryan

[Pyro]

Very tight bearing clearances would cause that. Did you plasigauge the engine?

 

I'm not sure the exact pressure the release spring comes in, but I would guess it would release by 90 psi.

 

What is the oil pressure when the engine is hot?

 

Try another gauge.

 

5w-20 would help.

 

A standard volume oil pump would low pressure at idle.

[cockerstar]

I didn't build the engine myself, but I'll ask him what the bearing clearances measured at.

We haven't run it long enough to hit temp yet.

We are also getting an intermittent rattling/knocking noise that persists for just a few seconds. The noise will stop on its own or if given revs or if shut down and restarted.

 

Oil plump is a melling m55 high volume.

 

I'll check on the gauge and see if I can snag one off of my camaro.

[jt1]

That's a lot. Double check the gauge with a known good one first.

 

Is it getting oil to the rockers? What kind of oil filter setup?

 

jt