[grandam1979]

How much oil should I expect a belt drive vacuum pump to pull from engine? I got 12oz after 6 1/4 mile passes. Thanks

[Kevspontiacs@aol.com]

Iirc GZ motorsports wants a thimble full after a quarter mile run

[GTO JONES]

A lot has to do where you are pulling from. I had mine pulling from the front center of the passenger side valve cover, way to much oil. I was told to move it to the center top of the valve cover, worked out great now I can drive 200 miles and only drain 6 oz. Before it would blow out the top of the catch tank all over everything at under 100 miles.

[John Langer]

2 weeks ago I made 10-1/4 mile passes and pulled zero oil out of the motor.

[gman005]

Set it up like this and your problem will go away. Ask me how I know. Lol.

[chuckies76ta]

Originally Posted by grandam1979

How much oil should I expect a belt drive vacuum pump to pull from engine? I got 12oz after 6 1/4 mile passes. Thanks

Maybe post a pic of where your pulling the oil/air from. The connection from the engine to the inlet on pump. I'm running 2 GZ pumps and hardly see any oil. Most time about a tablespoon of oily water.

I've seen issues with the catch cans mounted down low by oil pans that have caused to much oil in catch can.

12 oz is like 24 tbsp. that alot of oil. I have GZ larger vacuum pump on our 505 and only see maybe a tsp of oil after like 5 - 1/4 mile runs. I actually add oil to the inlet at the start to lube the pump.

As was mentioned where your inlet connection on the engine. It should be up front. Also do you have a relief on the engine or vacuum pump? and have you set it at higher rpm"s? In other words have you checked to see how much vacuum is on the engine through the entire rpm's?

[chuckies76ta]

Here's a couple pics of setups. Sorry sideways pics.

[Keith Seymore]

For those that are pulling from the center/top of the valve cover: do you have any baffling in there?

John Langer: can you post a pic of your setup? (I won't see you in person until NMCA Indy )

Thanks

K

[chuckies76ta]

No baffles in any of ours. That's with 3 different engines.

[John Langer]

I pull from the front of the passenger valve cover. I have a baffle inside the valve cover.

[Keith Seymore]

Do either of you know how much vacuum you are pulling at idle? Or at the finish line?

K

[John Langer]

Originally Posted by Keith Seymore

Do either of you know how much vacuum you are pulling at idle? Or at the finish line?

K

A hair over 13.1-13.4 at an idle and around 19 in the lights.

[grandam1979]

Valve cover has a baffle

[mgarblik]

Originally Posted by gman005

Set it up like this and your problem will go away. Ask me how I know. Lol.

I like that plumbing. Any deflector/baffle near the fittings?

[chuckies76ta]

Originally Posted by grandam1979

Valve cover has a baffle

Is that not the short valve covers. And also pulling from the middle of the cover. Get a cheap taller cover and connect from the front see if anything changes.

[chuckies76ta]

Originally Posted by Keith Seymore

Do either of you know how much vacuum you are pulling at idle? Or at the finish line?

K

Last time I checked at idle mine is low, around 5 or 6 inches at idle. I have it set to 11 inches at wot.

[grandam1979]

Originally Posted by Keith Seymore

Do either of you know how much vacuum you are pulling at idle? Or at the finish line?

K

I personally do not what’s acceptable?

[gman005]

I have no baffles.

[Keith Seymore]

Do any of you all run an adjustable restriction valve in the system?

(No further questions, your honor).

K

[chuckies76ta]

Originally Posted by Keith Seymore

Do any of you all run an adjustable restriction valve in the system?

(No further questions, your honor).

K

LoL, ask all the questions you want Keith. It's a learning experience for all of us. There is always something that gets over looked. And then we get that Ahh moment.



Anyhow, I've run the vacuum units all with a vacuum relief as you posted in the pic. (VCV101A)You can see mine in the picture that I posted.


This is what I have been told. If you run too high a vacuum on the engine it tends to pull oil away from the piston pins. Now other builders have told me it's an old wives tale. Actually I think the guy at GZ motorsports told me not to worry about it. I have settled on around -11 psi. All I'm try to do is get rid of any blow by at WOT. I'm not running a vacuum pump to increase H.P. I have 2 engines with GZ vacuum pumps, one on the street and one on the 505 cu in and no oil leaks at all. Added bonus.

Engine has to be totally sealed up for running a vacuum pump. No PCV installed either. I've installed a fitting on the appostive valve cover and connect a vacuum gauge and monitor it through the rpm's. The relief valve is installed on my vacuum pump and is fully adjustable for whatever you set it at. I put a cable tie through it as it came loose on on run.

One other thing I forgot mention is pulley sizes do affect operation of the vacuum pump. From my understanding it only needs to spin half the rpm of the engine.

Hope this helps.