ME Wagner PCV Operational Notes:

The Dual Flow PCV Valve can be in IDLE or CRUISE mode,
depending on driving conditions.
 IDLE mode has a low flow rate.
 CRUISE mode has an increased flow rate.
 The IDLE flow rate is controlled by the IDLE screw.
 The CRUISE flow rate is controlled by a combination of the user
set IDLE flow rate, and internal porting in the valve (porting is
precision machined and is not user adjustable).
 The vacuum level where the valve switches from IDLE to CRUISE
mode is controlled by the CRUISE screw (in Dual Flow mode)



Operation:

Upon engine startup, the idle circuit ball valve is pulled up and deadheads the passage as shown in the figure C (left passage) above. As this happens, the idle passage to the right in the figure C becomes throttled by the idle adjustment circuit. So, the initial vacuum turns on the idle circuit, BUT it is now throttled through the IDLE adjustment screw. Meanwhile, due to internal porting the cruise circuit feels full vacuum from the manifold, (figure A) not throttled like the idle circuit. If there is too much vacuum on the cruise circuit the ball check valve moves up the bore and seats against the bronze spring guide bushing. That action effectively seals off the cruise circuit and the flow characteristics are based solely on the idle circuit throttle position. That is acceptable, because in a higher vacuum scenario, more flow is provided by the higher vacuum. Once more throttle is applied or “cruise” mode is activated in the ME Wagner (a vacuum level slightly less than idle) cruise circuit feels LESS vacuum in the manifold as load increases. The vacuum felt on the cruise ball check valve decreases, therefore the spring tension set by the user now pushes the check valve ball DOWN. Once it clears the cross passage plug bore on its way down (which connects the idle side with the cruise side) full un-throttled manifold vacuum from the cruise circuit AND the idle circuit become mechanically in parallel. The net effect of this process creates a higher flowrate through the PCV valve. This operation is often misinterpreted by users, thinking that more vacuum pulls the cruise circuit ball valve up into the brass spring guide bushing creating more flow. However, that is exactly the opposite of how it works. If more vacuum is present and pulls the ball up the bore, it blocks all the flow through the cruise circuit relying more on the throttled idle circuit at the higher vacuum signal. So, more vacuum on the PCV doesn’t create more flow except through the idle throttle characteristics. As load increases on the engine, manifold pressure drops, allowing the cruise check ball valve to drop uncovering the cross-flow passage, therefore increasing the flow through the PCV valve.

During the setup of the cruise circuit, you tighten the cruise screw until you see the transition in the cross-flow passage on a vacuum gauge. That part of the procedure is moving the ball check valve DOWN the bore with spring tension and manifold vacuum pulling against it. Once the ball valve clears the cross-flow passage you see the jump in vacuum on the gauge. You have activated parallel circuits with idle vacuum. Now the directions have you turn the cruise screw counter-clockwise until the vacuum gauge goes back to zero. That action REMOVES tension on the spring and ball check valve. The ball check valve moves UP the bore and moves above (or at) the cross-flow passage. The PCV is now back on the sole throttled circuit of the idle circuit. The last part has you turn the cruise circuit screw an additional ¾ turn to further reduce the spring pressure. That ¾ of a turn is the vacuum margin from idle to the lesser vacuum that is considered “cruise”.

In the event of reverse flow, both ball check valve seat against the bottom of the valve assembly.

The whole purpose of the breakdown is to explain the operation of the ME Wagner PCV valve and how it is tunable for any application.

KT

 

Very interesting. And adjustable PCV Valves certainly have a place.

 

True, they do have their place. I started the thread not so much as a pitch for any particular PCV system or component, but as another source of shared good information. I've stumbled across lots of inter-webs discussions on the ME Wagner and theories of operation. Most of them are incorrect with gross conceptional errors. I'm not affiliated with ME Wagner, but I have one and I wanted to know how it really worked - and pass that on. I had the isometric drawings, but they don't show everything. So I took mine apart and analyzed the internals. Once you compare the instructions with the internal workings it becomes clear.

I write all that to simply state: once we know how and why, we can better manipulate our projects for the best outcome.

 

Indeed! Understanding how things are ment to work is the beginning! Then once we understand how it's supposed to function, then, and only then do we get things dialed in, other than dumb luck of course!

 

Haha! Sometimes dumb luck is better than any knowledge or experience! I rely upon it heavily!

 

What I find amazing is that seemingly (and I'm talkng about pre- electronic and injection era cars) is that each engine/hp/manual/auto/aircon and car model seemingly has a specific 'value' PCV valve if we believe the OEM information.
Perhaps confusingly no supplier or oem seems to be able to quote what the specific value is for your car/engine and other ancillary combo's. If you choose to replace your pcv valve as part, perhaps of a major service you are reliant on the supplier selling you a PCV supposedly correctly rated for your vehicle.
After a major engine build I was experiencing significant oil consumption, seeming too much crankcase pressure and associated 'blowpast' and the typical blue oil 'haze' behind the car when winding-up RPM past 5000. Likewise, a blue haze followed when slowing down through the gears.
Part of the issue turned out to be an aftermarket dip-stick and holder. The tube and it's 'O' ring seal were a poor fit and (unknowingly to me for a while) the tube would lift and leak oil vapour (and oil) which ran back over the chassis and passenger side header........creating the blue haze. The engine wasn't burning oil!.
I chose to replace the dodgy dipstick assembly with a high quality billet unit. I compared the aftermarket dipstick level with the OEM assembly and billet unit........the 'high' mark was significantly higher than the OEM unit.........so I was filling to the higher level and creating my own 'windage' issues. Solved oil usage, windage and crankcase pressure issues in one go........and used a 'billet' oil filler cap with built-in PCV without resorting to the Wagner unit.

 

Glad you got it taken care of. Looks like your problem was independent of a PCV specific problem. I find the biggest problem with PCV in our older cars is lack of information. OEMs today put considerable effort into designing proper PCV systems. Older more rudimentary systems had thought put into those systems as well. When we modify our engines and depart from original specifications the crankcase ventilation needs also change. However, we don't know any of the flowrates, pressure / vacuum and it seems the information is hard to find if even available. So we slap some breathers on, or any PCV valve we find online or at the local parts store. The engine runs either way, so we move on. We generally rely on secondary indications to determine success or not. What I like about the Wagner PCV is that you tune it based upon tested displacement settings. These settings were tested and are going to be a good starting point for engines in those parameters. It still leaves some guesswork, but at least we're not blind.

Anyway, I certainly don't want to get into another PCV discussion in terms of how, or should I, or what's required, or what's best, cheapest etc... I simply wanted to help clarify what a popular tunable PCV valve was doing on the inside. I had seen too many explanations describing the cruise circuit exactly the opposite of how it really works.

 

If you want to do it the budget way you can go to the parts store and buy a few PCV valves and then sort them after how large the internal opening is and the stiffness of the spring. For my modified 454 LS5 I found the PCV valve for a 1995 vette LT1 worked the best.

 

Yes. Probably the best solution. You can buy a lot of PCV valves for $100 plus...

 

A am pleased you brought the subject 'up to the table' - it is something that is rarely discussed in detail. My post was purely to illustrate how easy it can be to go 'off track'with an issue, perhaps not realising the real cause.

 

Here is a better illustration of what I explained in post #1. I'm a visual person, so it makes more sense to me this way:

The idle circuit:



The cruise and idle circuit together:



I hope this helps users understand what is going on in a relatively sophisticated mechanical adjustable PCV valve.

Cheers!

KT

 

Wow! great write up as usual. Do you recommend one of these to use with a Sniper? I have ta fixed orifice installed now. If this benefits an EFI installation I may go to one.

 

Not necessarily. They do work well and are very versatile. They are tunable and can be used on almost any engine application. They are expensive. You could buy fixed orifice PCV valve for ever, before buying the ME Wagner. Some people care about PCV operation, some don't. If you enjoy the tunability and really controlling every aspect of your engine (and have some extra cash you need to spend) it may be for you. Do you need it for EFI to work, nope.

 

I've been considering one of these for a while, but I'm not sure it would solve my issue. I would love to hear more about what started you down the MV wagner route.
For me, when I first start my cold engine, the PCV seems almost closed. This is on my stock but modifed 350 that has a retro roller cam, and produces roughly 20 inches vacuum at idle (pretty mild roller cam). From what i remember, this is more vacuum at idle compared to stock.
The PCV causes extra air to get in once open, so since it's barely open at this point the air/fuel ratio is quite rich, like 12.3, until the engine is thoroughly warmed up, which is more than the choke coming off and getting to the 180 degree water temp. I would say about 20 minutes of driving.
At 20 minutes the oil is hot, and I believe more pressure is coming from the crankcase than when cold/warm. The PCV opens up much more because of this, and the A/F ratio goes way up, to like 15.1, sometime higher 16.0 when i let off the throttle going about 30 down the road. The signal to the carb idle circuits seems also to be reduced.
Has anyone else experienced anything like this?
Would some tuning with the cruise setting of the MV Wagner unit help with this?

 

I'm not not sure the ME Wagner would help you with your symptoms. It responds to vacuum signals from your manifold at various loads, so unless those parameters are also changing with your engine temperature, it won't be affected by temperature. Have you tried isolating your PCV system during a test idle and drive to see if that changes your AFR in a different way?

The ME Wagner offers you the ability to tune or adjust the amount of PCV air flow with two flow conditions. However, I don't think you can tune away what you are experiencing with a PCV valve.

A standard design PCV valve also operates off from engine load or vacuum. They won't open due to crankcase pressure unless you are pressurizing badly. If you are using a large enough breather system, that should keep your crankcase from pressurizing. You may be producing more crankcase blow by at warmer temperatures, but PCV valves generally respond to engine load / vacuum, not blow by pressure or lack there of. So, what you are seeing on the AFR could be independent of PCV. Also, PCV air flow is considered insignificant when the throttle blades are open under part load or more. So, generally, PCV is more of a factor with AFR at idle, but not so much during part throttle operation.



None of that probably helped you, but you may want to consider seeing what your AFR does without a PCV system and see where that leads you.

 

I have a Wagner PCV valve. It works great on cams with a lot of overlap leading to low idle vacuum. Also does a great job evacuating the crankcase and keeping those pressures down at all realms of operation. A street driven car spends a lot of time at idle and near idle. So for a large overlap cam it improves the idle quality significantly I found.

It's another tunable component like the carb or timing that can enhance the total operation of your engine. You can go and buy lots of PCV valves trying to guess which one will work. I don't think too many OEM vehicles came with 10" of vaccum at idle however, so lots of luck finding one to fit the bill.