PCV valve location

[sunman]

1973 stock truck 390. Fresh air in thru small filter that clips into air filter on drivers side.
PCV in cap ( or a rubber grommet) in back of pass side with hose into carb base plate.
I’ve had other pre 78 (non emission) Ford trucks that had the same.
The Bronco is missing the air cleaner with the small filter and hose that plugs into the grommet you can see on the back of pass valve cover.
Looks like Ford did it both ways
Drivers on left side

[Tommy]

The very nature of gases in an enclosed space and the principle of entropy means that even if there is a momentary local region of higher pressure, it will very quickly even out within the enclosed space. So if the crankcase pressure in one area (e.g., the driver side valve cover) were higher than that in another connected area (e.g., the passenger side valve cover), they would very quickly equalize. With all the blow-by pressure dumping into a common oil pan area, unless there was some system of intentional or unintentional one way valves inside the engine, I can't see how the crankcase pressure would be inherently higher under one valve cover than the other.

Credentials: BA Aerospace Engineering

[patrickt]

Originally Posted by Tommy

Credentials: BA Aerospace Engineering

Ehhh, I bet twobjshelbys has a BS in something, maybe everything....

[twobjshelbys]

Originally Posted by Tommy

The very nature of gases in an enclosed space and the principle of entropy means that even if there is a momentary local region of higher pressure, it will very quickly even out within the enclosed space. So if the crankcase pressure in one area (e.g., the driver side valve cover) were higher than that in another connected area (e.g., the passenger side valve cover), they would very quickly equalize. With all the blow-by pressure dumping into a common oil pan area, unless there was some system of intentional or unintentional one way valves inside the engine, I can't see how the crankcase pressure would be inherently higher under one valve cover than the other.

Credentials: BA Aerospace Engineering

Everything you say is true. But an engine is anything but a closed systemi. An engine has lots of moving parts that disturb the static environment. I do understand entropy. In fact, I got an A in Heat and Thermodynamics (one of my degrees, there are more).

Let's just say that which side defies intuition based on all of our static analysis. Intuition says that the system should be balanced with equal pressure on both sides. The empirical data supports that one side is suction and the other side pressure. The fact that the 390 (probably a FE) picture has an open cap on one side with no evidence of exhaust and the PCV (pressure) on the other supports that. The same was true on my Windsor with no PCV but with the K&N filters - one side had oil from the inside to outside and the other was dry. And similarly, if both sides were pressure, I'd guarantee you that Uncle Sam would demand PCV hardware on both sides. Noone here understands why it works this way, but the fact remains, it is a fact. It defies logic and intuition. Sorry, I'm not trying to define why it happens, only, from the beginning, reporting my observations. Sorry if you're looking for something beyond that, since you're not going to get it from me.

Also, while other engines may be interesting, the OP was asking about Windsors. It is consistent with my catch-can observations on my supercharged Shelby GT which was the 4.6L 3V modular combined with others that have put catch cans on both sides and observe they never "catch" anything.

So the message to the OP is: Leave the PCV where it is.

I'm not sure the consequences of changing it would be pretty: As configured, minute amounts of oil but certainly some amount of pressured gasses go from the engine to the air intake. I don't know the volumes or pressures involved. If you reverse the configuration all of a sudden the suction/vacuum side will pull stuff from the air cleaner area to the top of the engine. Think about it carefully. Then try it if you feel lucky but please report back here.

I still think Brent is the only one that can explain it. I'm not going to try to solve it myself. I'm no longer interested in investing research and learning for something that I will only use once, 20 years ago maybe, but not now. My brain is full. I'll look for an expert to explain (similar to drywall, there are experts that can do that).

[Gaz64]

Oil inside one breather filter and the other side dry is more to do with position front to rear of each breather. Are they both at the front?

Otherwise I still say can't happen.

PCV valve should be placed as high up in the engine, and so moving to the front of the engine, either side, is likely to have less splash oil go through the PCV valve. Factory baffles plates aren't very good, and some aftermarket are even worse.

Whichever side has the PCV valve, the other side is the fresh air inlet, and flows air in BOTH directions.

https://www.google.com/search?q=pcv+...ih=791&dpr=1.1

[SBSerpent]

Originally Posted by Gaz64

Oil inside one breather filter and the other side dry is more to do with position front to rear of each breather. Are they both at the front?

Otherwise I still say can't happen.

PCV valve should be placed as high up in the engine, and so moving to the front of the engine, either side, is likely to have less splash oil go through the PCV valve. Factory baffles plates aren't very good, and some aftermarket are even worse.

Whichever side has the PCV valve, the other side is the fresh air inlet, and flows air in BOTH directions.

https://www.google.com/search?q=pcv+...ih=791&dpr=1.1

PCV is front of DS valve cover; breather is at the back on PS valve cover.

Why would there be more oil splash at the back of the valve cover vs front of the valve cover?

[patrickt]

I think the only reason the cap is on the front of one valve cover and the back of the other is because both valve covers are really the same. When you put the cover on one side of the engine the cap is on the front and if you put it on the other side it's on the rear. I think that's the only reason.

[Gaz64]

Originally Posted by SBSerpent

PCV is front of DS valve cover; breather is at the back on PS valve cover.

Why would there be more oil splash at the back of the valve cover vs front of the valve cover?

I would say because of the rearward tilt of the engine.

[cycleguy55]

Originally Posted by SBSerpent

PCV is front of DS valve cover; breather is at the back on PS valve cover.

Why would there be more oil splash at the back of the valve cover vs front of the valve cover?

Because the engine lower at the back, and oil moves rearward under acceleration. Yes, oil also moves forward under braking, but the engine presumably isn't revving as high, so therefore not pumping as much oil.

[sunman]

Valve covers are baffled if you have oil coming out you have a blowby prob.
Here’s a photo of a 73 Ford 390 FE driver side and 86 Mustang 5.0 HO pass side.
The 86 5.0 driver valve cover has no holes.
My early Chevy small blocks had a PCV in the vent hole next to distributor and a vented cap in intake manifold oil fill tube. A big oil separator bolted in the lifter gallery. The valve covers had no holes, said Corvette on them, good times

[Gaz64]

Originally Posted by sunman

Valve covers are baffled if you have oil coming out you have a blowby prob.
Here’s a photo of a 73 Ford 390 FE
My early Chevy small blocks had a PCV in the vent hole next to distributor and a vented cap in intake manifold oil fill tube. A big oil separator bolted in the lifter gallery.

Note the blowby airflow has to make an abrupt turn which helps fling oil out of the air.

[sunman]

Thats the same PCV set up on the 390, in the El Chico racing..party..bus...???
There’s a Cobra painted on the rear bumper.
El Chico manager I bought it from in Texas (1982) said Shelby did the paint and put on the 65 C4AE heads and Hooker Comp headers, that Carrol was a friend of his


Life’s good
Party On

[LMH]

On production original leaf spring Cobras, the PCV valve is on the left valve cover.
Larry

[Harpoon PV2]

Originally Posted by LMH

On production original leaf spring Cobras, the PCV valve is on the left valve cover.
Larry

Not on the early small block cars. The 260 and I believe a few early 289 cars, there were no openings on the valve covers. The oil filler tube was on the timing cover right side and was also the breather. Would love to know what serial number when the street cars changed to oil filler and breather on the valve covers? The race cars changed almost immediately after the came here.

[LMH]

Originally Posted by Harpoon PV2

Not on the early small block cars. The 260 and I believe a few early 289 cars, there were no openings on the valve covers. The oil filler tube was on the timing cover right side and was also the breather. Would love to know what serial number when the street cars changed to oil filler and breather on the valve covers? The race cars changed almost immediately after the came here.

Yes, I know but the majority of production 289 engine cars had the PCV valve on the left valve cover.
Larry

[Armrer]

There were instances of PCV’s on either driver or passenger side, depending on carb setup of street 289s (post road draft tube) straight from SA. Have the pix.

[FredG]

The PCV on my Roush, which has nothing to do with Ford, is on the driver side. They built the engine and put it there. That's all I need to know. Fine by me.

[Harpoon PV2]

I think this might help with the question on where you can put a PCV valve on a ford engine. The article is from July 2016, and it is how to make a 302 Roller Cam engine look like a 260/289, to fit in a Tiger. https://teae.org/s22-replace-260-289-302-roller-cam/ In it, he states, "If necessary, you can move the baffles up closer to the cover surface but don’t run without them. They are there to keep oil from being sucked up through the PCV." Of course we now have spacers to raise the valve covers, but the baffles are key to keeping oil where it belongs! Then I notice in his engine photo, the PCV is on the right cover at the rear. I thought that was just personal preference, but every Tiger I could find had it in the same place. So I went looking for original Shelby Los Angeles Tiger, (LAT) valve covers. Sure enough, all of them had the oil filler tube on the left cover in front, and the PCV on the right cover in back! I am pretty sure that the guys at Shelby knew what they were doing, and most likely Ford had a say in it also.