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Discussion Starter #1
I'm going to machine my new aluminum Edelbrock valve covers to take a breather on one side and a PCV valve on the other, more or less following the factory configuration.

It would be far cleaner and neater if I run the PCV valve horizontally, through the inner wall of the valve cover, instead of through the (deeply finned) top. I have an OEM valve and found a Help! grommet that has a nice wedge shape to it, so the valve will go in near the top of the cover and be nearly horizontal.

Are PCV valves sensitive to orientation? Do they have to be mounted vertically? I can't find any information about this, or about aftermarket fitting of PCV valves.

For what it's worth, the covers are taller than the stock ones and the inlet on the valve will actually be a little further from the top surfaces of the head than the stock, vertical mounting.
 

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The PCV controls a gas under pressure, orientation should be irrelevant. The only thing to watch out for is the check ball in the valve. If it tilts at too much of an angle, gravity may keep the ball in the open or close position all the time. I would think that using a straight PCV valve would be ok.
 

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You will also need to install a baffle in the valve cover to keep from drawing oil into the intake.
 

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Another option too would be to machine through the intake manifold (NOT THROUGH A RUNNER THOUGH) :( so the PCV draws from the lifter valley. It would also be simple to install a baffle to the bottom of the manifold.
 

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Discussion Starter #5
Thanks, all. I will go through the side of the cover and be sure to put a baffle in.

Another option too would be to machine through the intake manifold (NOT THROUGH A RUNNER THOUGH) :( so the PCV draws from the lifter valley.
Just today I had a funny that resonates with this. There have been repair crews in front of my house, trying to clear the storm drains that run under my property to the creek. Third crew, this one I think with a camera, worked for two hours. I'm buffing some trim when the guy walks up to me:

Worker: "Hi, do you know how long this telephone pole has been her?"
Me: "The year nail is 59, so I assume it's been here since the development was built."
W: "Huh! They sank it right through the side drain!"

And no one noticed for 45 years... :)
 

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Discussion Starter #6
The PCV controls a gas under pressure, orientation should be irrelevant. The only thing to watch out for is the check ball in the valve. If it tilts at too much of an angle, gravity may keep the ball in the open or close position all the time. I would think that using a straight PCV valve would be ok.
I was confused by the presence of what looks like a gravity-operated check valve or plunger in the darn things, even though all the descriptions and claims are that it's 100% vacuum operated.

Several sources, including a technical response from Fram, indicate that PCV valves *are* completely vacuum operated, should work fine horizontally, and in fact are installed horizontally in some applications (Ford Focus 2.0, for one).

Case closed. Thanks for the feedback.
 
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