Moderate cam? Weak vacuum? M/E Wagner PCV valve

[gator68428]

I have a moderate cam in my 68 Firebird (236 deg of int duration at 0.050) and always had weak manifold vacuum. But a few years ago, after battling with the PCV valve and experimenting with it I realized that a stock PCV valve only starts closing at high vacuum. So with my weak vacuum, what little I had was leaking away!

Of course this was a known problem and luckily I stumbled across a solution. The M/E Wagner dual adjustable PCV valve. This is not spam, just a happy customer trying to let folks know there is a good option to salvage moderate manifold vacuum before going hydro boost. I was recently reminded because I received an email from M/E Wagner describing updates to their product manual and FAQs and product support, not a spam email. Only email I've ever received from them.

Anywho, once I installed the pcv valve a few years back my problems were solved and I've forgotten all about it. I have about 12 to 14 inches of Hg and that's only after putting in the adjustable valve that will provide enough resistance to preserve that vacuum. With my dual 8" booster, and my 1" master, my brakes work great. Anyone else have it, how's it working for you?

[Josue]

I gotta tell you, I've really enjoyed reading your posts lately!! I've seen you upgrade to Z06 brakes, I'd have bought your CPP front kit if I hadn't already started compiling my own C5 kit for the front, and your car seems like exactly where I'd like to have my '68 someday!

A post like this is just what I needed to get my hopes up about trying to go power with my brakes!! My car is just a mostly stock, worn out 350 that's likely never been rebuilt. It has this cam...

http://www.summitracing.com/parts/cca-51-222-4

...a Holley 600, Edelbrock Performer Pontiac intake, Hooker headers, and 2.5" exhaust with H-pipe and Flowmasters. The car has been my dad's for 20 years, but he wanted to get into some top down fun in his retirement years here, so he bought a '69 Firebird convertible (see link in sig for full story) and I bought this car from him to keep it in the family. We've always had people do the "engine work" for us though, cam install, tuning, etc. because we didn't know what we were doing.

Now with my ownership of the car, I really want to learn about these old things and how to take care of them. At the advice/guidance of a few friends on the Pontiac boards who think my setup could yield better performing results, I started to play with the timing and carb adjustments last summer. I must have a long way to go though, because I actually made my vacuum levels worse I think. haha They used to be a solid 11hg at idle, and around 14hg with some revs. Now they bounce around 10hg at idle.

I know Tobin recommends much higher numbers than that for consistent pedal feel, but I've also seen tons of guys on the Pontiac boards say they only have 11hg at idle and have no complaints about their power setups. I have manual drums on all 4 corners, and was all set to stick with a manual setup in hopes that somehow the pedal pressure wouldn't be AS bad if I had high performing C5 brakes up front, and LS1 brakes in the rear. I know that might have been a pipe dream though, since it'd still be a manual setup. I've consistently read that while they will perform better, my pedal pressure wouldn't improve at all.

I've recently decided to attempt a power setup though, because my car is a borderline daily driver, and I would hate myself if I at least didn't TRY to improve my pedal pressure on a car that gets driven so much! I'm going with a C5 master cylinder and booster setup that's been done quite a bit on here. I'm taking a leap of faith that I will be able to tune my setup for more vacuum (or at least find someone who can do it for me, since I really don't know what I'm doing haha) or just go with some kind of vacuum booster. Now with your recommendation of this PCV valve, I'm more confident that I will be able to get the vacuum needed for a power setup!

[gator68428]

Thanks Josh! Glad to be contributing.

Measuring manifold vacuum can actually be tricky, as I've learned. Try plugging the port to the pcv valve to see how much vacuum your car can produce, without the potential leak through the pcv valve. You should have good (14"+ Hg) vacuum with that cam. Make sure you don't have any leaks. Maybe idle up a bit... My car idles at 1000 b/c of my cam. It's driveable on the street and very tame. Has 420 rwhp (mustang dyno) which is likely about 490-500 at the flywheel with 10:1 comp on 93 octane.

When driving the car, under any conditions I recommend using a pcv valve. Esp competitive--autox, track, etc. Trust me. I learned the hard way and blew out my rear main seal (rope seal at the time) by not relieving crank case pressure properly, and oil coming out of any place it could... Now I have viton rear main and proper pcv and have good crank case venting and good brake feel. Also, as I'm sure you know, do not take a Pontiac to a road course/Autox without getting a baffled oil pan. The Canton pan works great. Don't want to learn that one the hard way.

[Josue]

That's probably why my engine has oil leaking out of any place it can as well! haha I attributed it to just being old, worn out, and needing "freshened up", but someone recommended putting an additional breather on the other valve cover instead of an oil cap for those same reasons, so I guess there's something to that!. I did so over the summer, but I doubt that was the ONE thing it needed to dry things up, I'm sure it's just in need of a rebuild. It runs just fine though, and has been very reliable over the years, so I'm putting it low on the list of things to do.

I've never heard that about the oil pan on these, I'll keep it in mind! I would like to get this thing on a road course someday, Mid-Ohio isn't too far from me, but that's after I get a fresh power plant for sure.

[gator68428]

Another FYI about Pontiacs that i learned through first hand experience. The PCV pickup in the valley pan will suck oil around left hand corners, after high rpms approaching the corner. Pickup is on the right side of valley pan. This was what lead me to stop using it, leading to blown rear main seal! Now that's all been solved, the placement of my M/E wagner PCV valve is on the valve cover. PCV port in valley pan plugged (horrible location for a pcv, haha). The other valve cover has a breather routed to filtered air coming in after the MAF (so it gets counted as well... custom built EFI cold air intake). I've been meaning to start a build post for my car but haven't gotten around to it.

[Josue]

Do it! I'd love to see what all you have done!

Sounds like your setup may be a little different than how I'd have to hook the valve up. How would you install on a carb motor?

[gator68428]

Its essentially the same with carb or EFI, just forget mention of MAF sensor with carb.

With carb, breather line gets routed to pull from inside the air cleaner. Other valve cover with PCV is the same in either case and gets routed to manifold vac. I will post a pic later.

[gator68428]

Here are two pictures.
M/E Wagner Pcv valve on driver's side valve cover.



Breather routed to cold air intake before throttle body/carb. (Mine is a 4 barrel throttle body that is shaped like a carb).
Custom 4" ID cold air intake fabricated from scratch with fiberglass with 100MAF.

[TheJDMan]

So where does one find this PCV valve? To be honest I think I have a similar PCV issue with low vacuum.

[Josue]

Why does there need to be a breather ran to the air cleaner? Is that just for this valve? Or should that be the case with ANY setup?

I don't currently have anything like that on my car...

[Josue]

So where does one find this PCV valve? To be honest I think I have a similar PCV issue with low vacuum.

I googled it earlier, didn't find anywhere other than the manufacturers website. $129 through them.

[gator68428]

Breather can be it's own mini dedicated air cleaner too. That should be the case with any setup.

http://mewagner.com/

[TheJDMan]

Just ordered one, hoping this will help stop an annoying oil leak. Thanks for the info!

[SRYACHT]

This is great information. I am in the middle of a 496 build with a pretty healthy lift cam. I just installed 2002 F body disc brakes all around on my 1966 Chevelle and it's going to be questionable wether or not there will be enough vacuum to run the brakes. This could be a great option to try before adding a vacuum canister. Thanks for the info..

[Josue]

http://mewagner.com/

Let us know how it works out for you!

[kimosabi]

My new build should get 13.5" of vacuum but I have a stock AC Delco PCV valve. According to what you guys are saying it's not gonna open? I don't know yet because the engine is waiting for pushrods before I can do first startup.