[LenCaverly]

I don't know how many have experienced this but i bet its not uncommon . Think about this, At high rpm there is quite a lot of blowby and in most cases it has to escape through the breathers in the valve covers, so you have blowby fighting all the oil that is trying to return to the pan. If you vent the crank case below the heads then that allows the oil an easier path back to the pan. I've seen a 15 lb increase above 6000 rpm by venting the block at the fuel pump opening. The next best place would be the valley pan but that may restrict oil also if the valley is reinforced and the middle is filled.
Len C

[Lee]

I saw a dyno curve that was a bit unsteady at upper RPM, that became steady when a 1/2-quart of oil was added.

[Dragncar]

As long as the pickup never sucks air how could blowby theoretically effecting oil drainback have any effect on oil pressure at all.
Has anyone made a fitting for taking vacuum at the mechanical fuel pump location ?

[Herb Hagan]

Originally Posted by Dragncar

Has anyone made a fitting for taking vacuum at the mechanical fuel pump location ?

Too much oil suspended inside the timing cover to pull vacuum from this location and it will overflow a catch can on a single pass... don't ask how I know

[Skip Fix]

A 409 motor I bought in the 70s had been run in a roadster chassis and the guy had one of those big aluminum 90 degree baffled vent housings mounted on the side of the oil pan. Had a leaky sleeve so I got screwed on the motor but it did have a rare factory aluminum Z-11 water pump on it.

[Gary H]

Originally Posted by Dragncar

As long as the pickup never sucks air how could blowby theoretically effecting oil drainback have any effect on oil pressure at all.
Has anyone made a fitting for taking vacuum at the mechanical fuel pump location ?

I take my vacuum reading from a fitting attached to the fuel pump block-off plate. Mine is recorded though my data logger and it has no issues doing it that way. Steady readings throughout the runs

[LenCaverly]

I didn't say to pull vacuum there just vent it there. I've run a piece of bent heater hose off a block off plate at the fuel pump on the dyno and seen no oil. It is not going to help a motor that has excessive blow by. I believe the reason it helps oil pressure is because less oil gets trapped in the valve covers.
Len C

[Dragncar]

Originally Posted by Gary H

I take my vacuum reading from a fitting attached to the fuel pump block-off plate. Mine is recorded though my data logger and it has no issues doing it that way. Steady readings throughout the runs

The Steffs pan I had made has a 1/8 " pipe bung with a baffle for taking vacuum readings.

[rod cole]

If you want to see this in action just take a stock Pontiac and run wide open 2 miles and watch the oil pressure drop to zero as all the oil is in the top of the motor. Happened on more than one car/engine for me.

[slowbird]

Originally Posted by rod cole

If you want to see this in action just take a stock Pontiac and run wide open 2 miles and watch the oil pressure drop to zero as all the oil is in the top of the motor. Happened on more than one car/engine for me.

Stock heads or aftermarket?

[Dragncar]

I did a ring and bearing job on a friends 352 Ford FE. Ran great, it was in a Camper Special with low gear and a granny low 4 speed. He want out drinking and decided to race some car on a long 2 mile straight stretch. Blew a hole through the block. 5 qt engines and I told him he drained the pan.
Built him a nice 390 after that, very nice engine. I said to him, don't do that of the same thing will happen.

[steve25]

Some people say these are not worth it, not me!

[LenCaverly]

This is more related to aftermarket heads as some of them don't have the open real estate around the pushrods ( edelbrock) and are more prone to holding oil up top.
Len C

[Dragncar]

Originally Posted by steve25

Some people say these are not worth it, not me!

Got it covered.

[jimmy daniel]

Originally Posted by Lee

I saw a dyno curve that was a bit unsteady at upper RPM, that became steady when a 1/2-quart of oil was added.

That’s true on mine. First race after oil change if I see oil pressure start to wiggle and drop on my Racepak I can add usually 1/2 quart and it’s fine from then on. Without the Racepak, I would never know this.

[ta man]

2 gauges I always look at when crossing strip..fuel pressure and oil pressure.

[charlie66]

You can also put a exhaust evacution system on it. I have mine in the valve cover . At 35 pounds of boost i have a solid 90 psi of oil pressure.

[Half-Inch Stud]

Reminds me to add that Oil Pressure light that uses a Reverse Lightbulb. Stock Oil Pressure idiot Switch with cube relay is good enough...right?

[Todd1035]

Too much oil going to the top of the engine. An inherent problem with Pontiac oiling. The short fix is to keep putting oil in it till it stops. A stock Pontiac oiling system with a 60 pound pump and .030 restrictors will flow 12 GPM at the filter housing. A lot of that oil gets caught up top and takes time to drain. Ask my why I know. Lol

[421mike]

I guess that's why Pontiac put those 8 or 10 quart pans on the early super duty 421's. I know mine never sucked dry even with the 80 lb pump.