2x4s tunnel wedge and PCV

[Michael C Henry]

I have a Dove tunnel wedge 2x4 intake. Currently their is a 90° PCV valve in each valve cover. They each are vented to a S&H air cleaner base just inside the element. The left valve cover is going to the front carb which is the primary carbruetor. The venting is making the element a mess and coating the carb including the air bleeds. The engine has the breather stack in the center rear and the right front oil filler tube with push on breather in the intake manifold. The left valve covers PCV valve is towards the front and is close to the hood edge not much more room left.
I'm looking for ideas and examlpes on redoing the PCV system . I've thought about running both PCV valves to a Y then a single PCV valve actually controlling the flow into the under side of the intake plenum. Thoughts?

[SCOBRAC]

PCV valves are designed to operate in, well... a vacuum from the intake and not the aircleaner. It would make more sense to simple stick a breather in the valve cover.

Some engines work better (leaner) with a PCV installed. If yours does simply plumb it to the back of the intake.

[Loadco]

I'm just using one PCV valve. It is attached to the forward carb at the vacuum fitting in the base plate of the carb. I have a oil fill/breather cap in the other valve cover. This setup works fine with one exception. The left bank of cylinders run slightly leaner than the other side due to the PCV drawing it's air below the throttle plate. You can see pictures in my gallery.

[J Persons]

You may have excessive blowby. If your engine is healthy, and it's sucking oil, try adding a baffle below the PCV(s). If that fails, you might try an air/oil seperator. It's a container that internally baffled or filled with a media that will trap oil vapors. The lines from the PCV attach near the bottom, and the line to the carb comes out the top. there is a drain petcock on the bottom, and depending on your engine and how much you drive, may require emptying about once a week.

[neverwouldof]

I'm having exact same issue i believe.... 427 SO with tunnel wedge and it continues to leak oil out of the breather filter. Not a huge amount but enough to make a mess on valve covers. ( i love to drive but not much of a mechanic) Is that an issue with the way the engine is setup or just normal? my oil pressure runs 65-70psi and it runs through oil cooler. can someone put a link or names of the fix? thanks for any help....Keith

[Michael C Henry]

I'm also running about the same oil pressure. I have the Precision high volume oil pump with the provided shim installed. I need to remember to let the oil warm up before getting in to the throttle. The engine is realitively fresh. The 400 miles I put on it the week before last is the most it's seen yet. I have the black finned lemans valve covers . The addition of the Mobile 1 full synthetic oil that weekend may be impeding breakin . The oil temps fell. I'm hoping the rings will seat some more. I'd like to keep the two PCV vents running into one line and then through one PCV valve for flow control. I'd think that the flow split over two valve covers would lesson the volume form each so not to draft as much oil into the system. If that can't be done I'm thinking a twist in breather right side and the 90° PCV valve I allready have in the left cover routed to the hose and fitting I have located in the bottom of the Plenum. Does the PCV valves depend on being upright as in the valve cover so gravity is acting on the valve?

[speed220mph]

Mine blew oil out the breathers until I installed a single PCV valve as shown. Heads are tunnel ports with 2X4's up top on tunnel-ram manifold. Used stock oil-filler cap that's well baffled to prevent oil being sucked into intake and an inline PCV valve. Drilled and tapped manifold on opposite side to accept a bushing and AN fitting with 270 degree swivel with pushlock. Setup works well.

[Michael C Henry]

Where would I get a cap like that and what would I call it ? That looks like it would work for me.
Any identification would be a great help. Motorcraft website only shows a drawing and leaves a lot to be desired.
I have identified painted cap is FORD #DOAE-6A66-A says "AUTOLITE"
Chrome version is Ford #C8AZ-6766-B "MOTORCRAFT EC-2 "
There is also ,if height is limited, a Ford D1ZZ-6766-A = Motorcraft EC-508 in chrome, wide and short with bumps for gripping
I've been calling and drivnig to stores and junk yards ,searching the web (mostly E bay). I've collected some information as I went. Mostly burning time and gas. So! to get this project under way I took an afternoon off to get home to the computer for the E-bay aution closing time on a chrome Motorcraft EC-2 cap. I'm imbarassed to say what I paid, but that part is over with .Those oddes and ends are like GOLD . I will be shopping the swap meets.

[Michael C Henry]

speed220mph
The EC-2 breather cap shown appears to have an open elbow not a PCV valve. What does the rest of the engine openings look like? I was just at a nearby shop that had a bunch of 427s. The owner said I need less breathers and one PCV to pull a vacuum on the crankcase.

[Cobrabill]

PCV?We don't need no stinking PCVs!

Oil puke tank on the fire wall and two road draft tubes.

[speed220mph]

Michael: The PCV valve is under the manifold in-line between the cap and pushlok at the manifold. Different size lines ensure the PCV valve is correctly oriented. As for where I got the cap, it was on shelves in my stack of stuff. All I know it is a Ford something, probably off a mid '70s Cleveland or M-series engine.

Cobrabill: I was thinking about using a puke tank, but with a hidden PCV valve in the system. Then I reconsidered: Why put all that excessive junk in the system when a little old PCV valve will pull a vacuum, albeit small, on the crankcase to evacuate corrosive vapors, keep oil mist off the rocker covers at the breathers and reduce overall weight and complexity. That little old "stinking PCV" valve does the job.

[Cobrabill]

Tom-i have the puke tank with no PCV and have no misting problems.

[speed220mph]

Cobrabill: The misting on my car was under the breather caps. The mist from your engine is going out the road-draft tubes. I suspect you're getting some oil under your car if the vent tubes are doing their job, i.e., venting the crankcase and puke tank.

Back to PCV valves, they have no downside, so why not work one into your engine's crankcase-venting system? It ensures moisture and other damaging vapors boiled off oil in the crankshaft is removed, extending the life of your engine. And this is done without any drain on your engine's power. Maybe because it's considered a anti-pollutiong device?

[HSSS427]

Have an Earl's breather in the rear driver side valve cover and a matching cap with the PCV built in and an AN -6 fitting on the front driver side cover. The rear goose-neck breather is now blocked off as I was getting a lot of mist being thrown out of that breather.


Here's a close up of the breather retainers I installed which seem to seal and hold the breather caps down much better and have baffles built in.


Summit part # CSI-680 $49.95

So far so good

[Michael C Henry]

are all PCV valves pretty much the same? If they are then why so many different applications? A lot of the valves look the same ,if they wern't still in the package you couldn't tell one from another.. Some have addon plumbing. Is there really a difference or just find one that fits?

[speed220mph]

Michael: Positive crankcase valves are calibrated for specific engines. The PCV system on an engine is a controlled vaccum leak as are carburetior or FI throttle plates. The bigger the engine, the more air--crankcase vapor--must be evacuated by the PCV valve. Therefore, PCV valves are calibrated to the requirements of the engine. However, if you choose a valve which was used on a larger engine such as 6--8 liters, one valve will work.

The thing you hear when shaking a PCV assembly back and forth is a spring-loaded shuttle valve. This valve is forced against a spring by manifold vacuum and crankcase pressure. Thus, it maximum flow restriction at idle and wide-open throttle to limit air/fuel mixture leaning. The spring pushes the valve open to provide maximum flow during part-throttle operation. So, if your engine is jetted toward the lean side, the addition of a PCV system will require slightly fatter jets.

[Carnut427]

Originally Posted by Michael C Henry

are all PCV valves pretty much the same? If they are then why so many different applications? A lot of the valves look the same ,if they wern't still in the package you couldn't tell one from another.. Some have addon plumbing. Is there really a difference or just find one that fits?

If you check the application guide for a specific year, you'll usually find that all V8 engines of a certain make used the same PCV valve; 6 cyl engines usually used a different one. This is true for both Ford and Chevies, so the difference is mainly what will fit; I'd personally stay somewhere near the same year as the engine you have in case things such as computers etc. affect them. Don't know that they would, but just to be safe...
JMHO,

Dan

[fsiewert]

PCV valves are very different. Not just in size but in the amount of vacume it takes to open them up. The theory of the PCV valve is to create a vacume in the crankcase, valvecovers, lifter vally, so oil will not try to force it's way out of the gaskets and past seals and rings. the vacume is created from intake manifold vacume being used through the PCV valve. When the throttle is opened manifold vacume drops and the PCV valve closes to keep the vacume in the crankcase, to keep the oil in.

Readers Digest Condensed version.......
PCV won't work if:
Too much cam...not enough manifold vacume
Too much blow by past the rings
PCV valves are rated by vacume so you may need a different pressure PCV valve.
Some are spring loaded and some work on gravity..make sure they are in the position intended.
They won't suck at WOT (wide open throttle) Not supposed to.
The hookup to the manifold should be into the main plenum of the manifold because there is a most constant vacume there. Not a manifold runner. (too many pulsations) That's good for Vacume brake booster.
The vent should be in the opposite side valve cover to vent the WHOLE engine.and the higher the filter the better. That's why most are vented from the aircleaner. Clean air goes in that tube and out the PCV and is burned up in the combustion chamber with the air-fuel mix.

Now that I have truly mixxed you up, you should know everything there is to know about PCV valves.
Fred

[Mr427]

Hi!

I have been reading the posts above and I see some really nice looking systems that you are using for crankcase evacuation.

The positive crankase ventilation system was mandated by federal law in september 1966. Its sole purpose is to capture the very toxic mixture of residual air-fuel mixture that gets blown by the piston rings and into the crankcase, plus airborne lube particles that form insde the crankcase. It is a very violent place to be on any given day!

The PCV valve must be located, either in the center of the intake manifold or on either valve cover. It must be completely airtight, mounted in a gromet or pressed into a sealed container like in the pictures of the Summit setup above. This is where air gets sucked out, but only as far as compression pulses will open the check ball inside the valve casing, assisted by the engine vacuum signal.

If you suck out air, you need to have a place for it to get sucked in too. That place is the breather on the other side of the engine, or as on older FEs, through the filler / breather cap on the filler tube on the intake manifold. This, however is not an ideal setup. If you want maximum cleanup effect, you really need to have the exit and entrance on the valve covers. This is due to the fact that oil mist, gasoline fumes and water vapors tend to rise to the roof of the building, i.e. the valve covers. Since the FE with its Cobra LeMans or Baldie valve covers is one very tall building, this is where your culprit is going to reside and cause a mess, causing oil stains and what not all over.

So, in my view and from what I have read, the valve covers need to be the north and south borders in this war.

The PCV valves are made in a myriad of configurations. What varies is mostly diamter and weight of the check ball. This is regulated by the vacuum signal that each particular engine is known to have. That means STOCK engines that idle smoothly AND have a regualr vacuum signal at 650-700RPMS.

As you get into more aggressive cam profiles, the vacuum signal starts to change and deteriorate in more ways than we can count. As we get into degree territories above 235-240° @.o50 on the FE, you need to look at other options. Notably vacuum pumps (with aggressive cams and low pressure piston rings) and / or oil accumulators and scavenging systems that operate on header collector negative pressur. But on those applications you are always having to endure very discomforting and potentially deadly vapors inside your cars as you sit at the local stoplight.

The PCV system is the single most effective, least expensive and most reliable method of pollution control ever installed on an internal combustion engine.

bye

[Carnut427]

The rush of the fuel/air mix by the PCV hole in the intake, carb base plate, where ever, creates a vacuum on the PCV valve, so that the PCV system also works under acceleration, and there is enough vacuum under most other conditions, such as cruise, that it's actually working most of the time. At some point in spirited acceleration the PCV system may not be able to handle all the blowby. This is why you see puke tanks, scavenging systems that operate on header collector negative pressure, etc.
My 2 cents...

Dan