Yes, I've done it.
Yes, the more modern day cars have a PCV system (to evacuate crankcase vapors) WITHOUT an air inlet source.
Does it work with ONLY a PCV valve connected to a manifold vacuum source? Seems to work fine, I've not seen any adverse effects--------yet.
Does EVERYONE say you MUST have BOTH an inlet (for fresh air) and an outlet for crankcase vapors? Yes.
Are the right? Now that is the BIG question!!!!! I've read articles in automotive magazines that say it will work OK.
The last car that I did this to (PCV outlet only) was a friend's 66 Corvette with a built 383.
The mid 60s small blocks had an oil filler tube at the front of the manifold and the tube had a fitting for attachment of a PCV valve and then a hose from the PCV valve to a manifold vacuum source (base of carb). As far as I know, it's been fine ever since (3-4 yrs ago).
For a BB, the setup would be the same. Install a PCV valve in a grommet in one of the valve covers and connect it with a hose to a manifold vacuum source. Will that work OK? I really think so.

 

Please remember that the "fresh air inlet" side of the PCV system is ALSO an outlet when there's high blowby and no manifold vacuum. It is for that exact reason that by the late '60's--early '70's that the fresh air side was plumbed up to the air cleaner--the backflow still went down the carb throats.

Failure to provide this secondary outlet would result in excess pressure in the crankcase leading to leaking seal.

 

Please remember that the "fresh air inlet" side of the PCV system is ALSO an outlet when there's high blowby and no manifold vacuum. It is for that exact reason that by the late '60's--early '70's that the fresh air side was plumbed up to the air cleaner--the backflow still went down the carb throats.

Failure to provide this secondary outlet would result in excess pressure in the crankcase leading to leaking seal.

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Exactly
PCV valves are a great thing to have on a street car & work very well to remove a lot of contaminates from the crankcase & help to keep your engine clean
But they only work when there is a vacuum in the intake
Now consider when you have the most pressure in the crankcase
It is not at idle & cruise where you do have vacuum
It is at full tilt
How much vacuum do you suppose you have at full throttle assuming you do not have a 2bbl on your ride
Answer,,
None
So,, your PCV has reverted to being nothing but a small & somewhat ineffective breather

I know of no factory setup that did not have some sort of fresh air intake which also acted as a breather when you had no manifold vacuum

In my opinion you should have a breather

 

most modern cars still source fresh air in the duct between the air cleaner box and the throttle body and a pipe to a valve cover.Not much has changed,they still source fresh air behind that has ben metered behind the maf sensor.

 

the blowby is the source of the water vapor, not the cure for it.

most PCVs have a small opening, look at a few. What Schurkey said about the two-way nature of the fresh air inlet. most engines will easily overwhelm the flow capacity of the PCV at heavy throttle/high RPM usage. If you allow pressure to build in the crankcase (this includes the valley and the valve covers) bad things will happen. Usually starts with pitching the dipstick and moves on to the next weakest seal.

 

Did it on accident once... blew the dipstick up a bit and blew oil everywhere, rebuilt 402
Forgot to cut out the hole out in the bottom of the new breather grommet on the opposite side valve cover with the breather.

 

this is very interesting, as I'm going through problems with crankcase pressure.

Right now im running one open filter breather and one PCV, im having oil blow out the breather and go all over the place.

Here are my plans, let me know if this is a bad idea.

I just bought two of these http://store.summitracing.com/partdetail.asp?autofilter=1&part=TRD-9242&N=700+115&autoview=sku

im going to replace the open filter element breather on the passenger side with one, drill another hole on the backside of the driver side valve cover and install the other one. Then im going to run a tube from one to the other. I have a pcv on the front of my driver side valve cover that runs to the back of the mnaifold or carb. i have to check that.

here some pictures of my current setup so you can take a look.

dont forget im running an open air filter breather, not that closed one shown.

 

this is very interesting, as I'm going through problems with crankcase pressure.

Right now im running one open filter breather and one PCV, im having oil blow out the breather and go all over the place.

Here are my plans, let me know if this is a bad idea.

I just bought two of these http://store.summitracing.com/partdetail.asp?autofilter=1&part=TRD-9242&N=700+115&autoview=sku

im going to replace the open filter element breather on the passenger side with one, drill another hole on the backside of the driver side valve cover and install the other one. Then im going to run a tube from one to the other. I have a pcv on the front of my driver side valve cover that runs to the back of the mnaifold or carb. i have to check that.

here some pictures of my current setup so you can take a look.





dont forget im running an open air filter breather, not that closed one shown.

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Hi Brian,
I think most of your problem may be where you have the breather & PCV mounted
The outside of the cover is not the best place as the rockers throw a ton of oil around in there
This is especially true if you have the hole located directly over a rocker.

Do you have baffles or oil seperators of any kind?
If not you are throwing oil right into the PCV & breather
Not a good thing


Hi Walter,
Thanks, :beers:

 

installing two and running a hose between them won't help at all. instead of running a hose between them run a hose from both of them to a vented catch can on the firewall. find a can that can take the 1/2" line. Neckdowns to 3/8" won't be helpful.

Any idea why your rings are allowing so much blow-by? That's likely the real underlying problem. Are you sure the breather on the passenger side is open, not blocked off by the grommet or an internal baffle? If your rings are good the system you have should be adequate provided the flow in and out through the breather is not blocked or restricted..

 

where do you usually mount the remote breather?

 

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Usually under the hood

On the firewall, front of the head on a bracket, anywhere there is room
Preferably above the valve cover so the line runs down hill to the engine.

 

haha, okay I'll be working on it this week and i will contact you if i need one. Thanks Mike

 

I believe i fixed my crankcase problem.

Here's what i found.

My pcv was not functioning correctly. I got a new pcv and installed it and nothing. Then Ron (bikeron) stuck his finger in the grommet and laughed pretty hard at me. He said there's your problem. The grommet only had a little slit in it and the breather was wide open. So the pcv wasn't working and the breather was sucking way too much air. So we got a new grommet for the passenger side breather and a new grommet for the drivers side pcv and make the suction equal. Seems to have helped, no more oil out of the breather and the engine idles much smoother. I will wipe everything down today and see if it stopped my oil leak problems.

 

I believe i fixed my crankcase problem.

Here's what i found.

My pcv was not functioning correctly. I got a new pcv and installed it and nothing. Then Ron (bikeron) stuck his finger in the grommet and laughed pretty hard at me. He said there's your problem. The grommet only had a little slit in it and the breather was wide open.

Is that grommet the type where it is designed to act like a baffle? They do not let enough air flow through it IMHO. Cool.....glad you fixed it.