Which PCV valve flows best?
 

Having read several threads on the subject of crankcase ventilation questions come up regarding the amount of flow of the PCV valve. Discussions have varied as the how much flow is necessary at idle or cruise especially on modified engines with "rowdy" camshafts. I saw in one tread where the stock PCV valve flows 4 cfm max with little flow at cruise or wide open. The following thread on this got me thinking:
https://forums.maxperformanceinc.com...d.php?t=864137

Sugestions have been made that the Wagner PCV valve is adjustable to flow rate and does a better job than the 4cfm stock type PCV valves.

https://mewagner.com/?p=444

Before investing the cost of a set of Crower 68404 valve springs on this PCV valve, I would like to know if anyone on the forum is using the Wagner PCV valve and found it to be better at providing crankcase ventilation overall than an over-the-counter PCV valve?

Appreciate your thoughts on this.

I like the idea behind the Wagner pcv but as far as I'm aware they only make one style and the car I'd like to experiment on uses a different style so it's a no go for me.
I would have thought by now since they've been around for years they would have expanded on their design and model offerings.

For decades I've used the stock pcv without issue and very low idle vacuum. Wasn't till I went to EFI and tried a fixed orifice that it became a noticable problem. I went back to the stock pcv.

I have a buddy who stacked his PCV valves, picked up 40hp.

I'm not sure what this means exactly. Could you elaborate please?

Stacked is Probably 2-more in parallel.

Just re-carbed my 455 and, well left the PCV hose unhooked and drove around; No oil mist, but gotta re-constitute the vacuum path for the good long term benefits. Oh yea, the Q-JET needs more Accel-Pump shot to optimize Part-Throttle transition.

I've had a Wagner on my 455 for 7 years. I tried all the suggested HP PCV's and had a slight drip out of the rear main. (50 year old factory rope) After installing and setting up the Wagner, I very seldom find a drop under the car. Worth the money? Some will tell you no. Me? Yeah, I'm very happy with mine.

https://forums.maxperformanceinc.com...0&d=1565650389

i switched to a wagner pcv. bought a cheap manometer and was able to clearly see higher crankcase vacuum at idle and under load vs several off the shelf pcv valves.

also reduced oil leaks noticeably.

formulajones what do you mean by different style? if you mean valley pan instead of valve cover, they make an adapter grommet if i recall.

I'd like to see a straight style to fit the molded hoses. The 90 really doesn't work unless I want to reconfigure the lines and wouldn't look quite right. Don't want to ditch the molded PCV lines, they are kinda expensive, lol.

gotcha ... my engine compartment looks like it was plumbed and wired by a couple of drunken penguins, so the straight PCV valve is the least of my worries :D

LOL

My first impression is that you are using the Wagner PCV valve to cover up other issues with the engine: (Oil Leaks, Ring Seal, etc).

But your engine and whatever works for you.

Since the Big 3 all used PCV Valves of the same design and with approximately 4.5 cfm flow, amazing how their stuff did such a great job over many years with a very low cost part.

Tom V.

M/E Wagner makes 2 styles and have an adapter so it should work in nearly all cases. And they have since modified instructions to have a higher maximum flow than you could before with their old instructions setting it up.

Works great in line from the valve cover to back of EFI base for me in a high flow fixed setting.

I dont have the part numbers in front of me but i tested from memory a Pontiac and a SBC PCV valve both clean and new you can simply put to your mouth to test, ... you dont have enough lungs to close the valve but all you have to do is push the valve closed and you can get a comparitive feal for how much air is passing..

the SBC valve passed far less air than the Pontiac one

Yes, this brings up a point that many miss. Physically many of the PCV valves look the same but there are many different ratings on them depending on application intended. If you look through the book they have a different PCV part number for all kinds of different OEM engines from the 60's through the 80's. I remember when PCV's used to just hang in the "help yourself" section and everyone would just grab one that looked like it would fit.

For instance, my Chevelle takes a PCV valve that looks like this one

https://shop.advanceautoparts.com/p/...003/12448224-P

Problem is, there are literally more than a dozen PCV's that look like that, and they all don't flow the same. Now if Wagner made one in this configuration which is the more common style and fits at least 5 different classic cars I have here, I might be willing to try one for giggles and experiment a little bit.

I would bet the engineer that spec'ed out a PCV valve for a given engine had a target CFM of fresh air they wanted to pass through the crankcase at idle, so based on idle vacum you varied the calibrated leak through the valve to get that target
plus the inner spring tesion could of been a variable as well to change cut in and out the metered orifice

I think you are correct. As an example our 69 Z takes a specific PCV if you look through the old books. Same straight style I posted above but rated differently than my Chevelle or Firebird that also take that same style.

Reason being is the 254 @ .050 camshaft and lower vacuum at idle than most other engines of the day.

I actually searched out an NOS PCV for the car because I didn't feel some of the offerings today were true to what they should be just based off what I was reading and how some part numbers have become conglomerated.

That's where I think this Wagner could be a benefit as it could be adjusted to fit some of those scenarios where a good PCV is hard to find. Unfortunately the 90 degree body they make just won't work for me. I also don't know if I could make myself look at that bulky thing sitting on my valve cover LOL

Probably ... but as posted below, I don't really trust what I am getting at the store any more ... seems like part numbers have been consolidated. I have about 13" of vacuum at idle so figured it was worth a shot to use the wagner valve instead of risking getting a pcv valve that was not calibrated for a lower vacuum application.

After reading these posts I found Wagner's page of adapters ( https://mewagner.com/?p=540 ) where they have a valley pan adapter designed with help from Jon's Tri-power Service which looks feasible for most Pontiac applications. I looked closely at David's photo in post#6 and think that the Wagner just looks like some of the goofy smog stuff of the late '60's-early '70's that our engines had back then. I agree the appearance sucks but if the flow is good and adjustable, it could be very feasible for a rowdy camshaft. THe cost is not good but a re-build kit is availble so that mitigates the cost somewhat. And post#17 points out correctly : " I don't really trust what I am getting at the store any more ... seems like part numbers have been consolidated. I have about 13" of vacuum at idle so figured it was worth a shot to use the wagner valve instead of risking getting a pcv valve that was not calibrated for a lower vacuum application. "
Post #11 points out the use of the std 4.5 cfm PCV valve for the car makers has worked for years.

I appreciate all the responses to this thread. Much to think about here before making a decision. Thanks y'all.

If you know the number your after you can find old stock on ebay..

i remember PCV valves looked like they were a machined part saw very few of them back in late 70's think AC was the manufacture on those but formed sheet metal took over fast for cost reasons i expect

i just went to ebay and found what i was talking about, a thick body looks machined NOS AC PCV Valve CV 486 says for 1967 camaro 61-63 tempest 4cyl

That is a concern (with the Chinese knock-offs) being sold the last 10 years+)
But at one time the Delco (GM) and Ford valves did the job very well.

I have to keep remembering that a 1990s valve is not the same as the crap out there today.

Tom V.

Yes the correct valves from back in the day were what they call "spun steel" and usually had an ink stamp as well if I remember correctly.

Some of the more common ones aren't priced too bad but a correct valve for the 69Z for instance, I've seen 2 styles of the 746, one with a flat top I think, and the spun steel being the hardest to find can fetch $500 LOL

I just bought a couple CV486 to see what they are about

Have seen some aftermarket breathers with small holes underneath rather then large as stock would use / wonder if that would restrict the flow & cause pressure.

I'm guessing yes. I was experimenting with a fixed orifice PCV and found they all come with a hole way too small for the larger engines. I kept drilling it open in very small increments until I realized I needed a bigger change.