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Originally posted by Strange Magic:
Do you click neutral and shut the engine off right after the stripe?

That right there is enough reason to not do it that way.

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After years of experimenting and hearing results from my customers, I gotta say that Strange Magic is the only one who has successfully used the oil pan as the suction point for a vacuum pump on a wet-sump motor. How do you keep the oil away from the suction point?

You fire the fitting right into the side of the main cap. Non kick side only.

P.S. We don't run anything greater then about 6 quarts total in a wet sump engine. No need to. If your oil pump puts it up faster then it can drain back, then fix your poorly engineered oiling system.

After 1 pass today it filled it about half way. I think its sloshing under braking and filling the fill tube
Vacuum spikes in shutdown. Fitting is in front of valve cover but close to the head. General consensus is that its filing it because of that. Going to take second turn off this next pass and not use as much brake and sew what happens.

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Fitting is in front of valve cover but close to the head.

Terrible place to have a fitting.

This is where we put customers vacuum pump fittings when they go into a valve cover.

I use a fitting from Star Machine, it acts as a baffle, never an issue. If you can put it in the intake manifold under the plenum area you would probably pull even less oil from there.

I also use Star baffle and it does help. Turn it facing down and it helps to separate the oil from the air.

Still the reason it draws oil is because there is an air leak and so air is going through the motor pulling oil with it.

Looking at the picture above...Aren't the vac hose and nozzles going to be an issue? Maybe it just looks really close.

It seems to me than in a lot of cases, there is more going on than where you pull vacuum. I and many others pull from the front top of the valve cover, and have never had this issue. I pull virtually no oil on a weekend on my wet sump. Just moisture.

I have spent a good bit of time and effort playing around with different pull locations and vacuum levels and have personally seen the valve cover as the best location irregardless of engine design. One of the basic principles with a negative pressure environment is that the entire chamber sees the same signal (meaning anywhere within the internal environment of the engine, aka – chamber).

I have pulled upwards of 18HG down to as low as 5HG and when everything is optimal, the higher HG always seems to prevail. There are limits to what you can get away with and from my experience, its the front and rear main seals that are the limiting factor.

As many have already said, air “flow” promotes the oil getting picked up in the vacuum stream. If you have a pull location that is in an area that has direct alignment with exhaust oil stream, that will obviously be a problem, however I have located the pull location on the top surface of the valve cover (not the side top surface) and it is perfectly fine, you simply don’t want to put it directly above any of the pushrod/rocker/valve locations. Both of my own cars are this way and they will go many runs with no accumulative oil in the breather tank, this is at 15lbs HG.

I little while back I built a BB Chevy that was all of the wrong stuff, but was a “compromise combination” just to get the owner racing, it was pulling 13HG peak (with chrome rings – lol) and once all of the gremlins were sorted out such as valve cover leaks (junk covers) and front cover (Milodon Gear drive pinion gear cover leak) it was good to go using the left front surface of the valve cover as the pull location. Not many runs later it was severely overheated (owner forgot on turn on the water pump) and from that point on it would pull oil at just about any HG level. I think we know what happened here – lol, but the new owner lowered the HG level to the point of it being just an evacuation system and not a negative pressure system and called it good and continued to run it that way. The point here is that the air flow within the internal environment cannot be of any significance or it will most defiantly start extracting oil.

You can diagnose this problem using a smoke machine and/or even a low pressure air supply system such as 3 lbs psi and going over the external areas with a stethoscope. The one thing you really cannot do is replicate ring seal, engine off leak down tests do not fully represent dynamic ring seal during the running operation, that requires a different diagnostic approach. So first look for air leak sources that may not even show signs of oil leaks and go from there.

quote:

Originally posted by Wallace Cleaver:
After 1 pass today it filled it about half way. I think its sloshing under braking and filling the fill tube
Vacuum spikes in shutdown. Fitting is in front of valve cover but close to the head. General consensus is that its filing it because of that. Going to take second turn off this next pass and not use as much brake and sew what happens.

No, you either have a vacuum leak(s), or your rings are shot. If there is no air flow through the vacuum pump, there will be little to no oil in the tank. With a lot of airflow comes a lot of oil.

As said many times, check ALL places where it can leak! Timing cover, valve covers, distributor hold down, slip collar if it has one, fuel pump block off plate, oil pan, and lastly, front and rear seals.

Borrow/rent a smoke machine, you will be amazed how many leaks you will find!

My valve cover hold down bolts were leaking, had to put rubber o-rings between the nut and the cover.

Everything can leak!

Well, found the real issue. Block is cracked. Made that hit, went to run again and it was hydrolocked. #3 full of water. Tore it down, no signs of anything, figured it was a head gasket. Put it together, warmed it this morning. Went to retorque heads and one just wasn't right. Took #3 plug out and dumped water all over again. Guessing it's been bleeding compression in there for a few passes now. Certainly explains the sudden change. Thank you all for the great advise and ideas.