PCV on V8 - does the side matter?

RatLabGuy

RatLabGuy

You look like a monkey and smell like one too
Joined
May 18, 2005
Location
Churchville, MD
Currently my 302 has a very worn-out oil cap w/ the PCV sitting in the top of it on the driver side that needs replacing. The passenger side valve cover has an elbow fitting near the back that currently is connected to nothing, I'm guessing used to be a vent or something.

I'd rather flip these so that the PCV is on the passenger side right near where it connects to the carb and get it off the oil filler cap. Is there any reason why it would matter if I flipped sides, so the venting is going the other way? E.g. venting sucked in through vented cap on driver side, and out through PCV on pass side.
 
The closed breather is like a supply to engine, the PCV is a vacuum operated return back to carb. I don't think it'll work flipped.
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Now of course I'm sitting here pondering over this too. Maybe it will
 
We got the exact same vacuum reading no matter which side when we shot the "die-hard" theory of vacuum direction down several years ago...

But!!! I'm no sure of EVERY motor. But on a non-smog SBF / FE / or BBF it makes entirely no difference which side you vent and which side you restrict to a single direction... As long as you create positive vacuum you're good. I go for the least distance / easiest route to the carb so it just depends on if we're going with Edelbrock or Holley to which side we set motors up for Positive Vacuum.

Regardless, I am a firm believer that positive vacuum will extend motor life of anything over 75K miles. The proof is in the final break-down of any core that was ran without positive vacuum. Seen the valve cover become a mold for blow-by build-up with only room for rocker movement on a many of non-pcv setups. The motor essentially starves itself from oil due to blockage. Positive air flow and regular oil changes is the life of a motor.
 
It makes no difference which side the pcv is on. Just make sure you have the fresh (filtered) air source on the other valve cover. One side needs to pull fresh air while the pcv valve pulls it through the motor into the intake. Like 6BangBronk said, it is quite important to the life of the motor to evacuate the blowby gasses.
 
Yep no difference as long as the filter is on the other valve cover.
 
Roger.
That's what I thought, seeing as the engine is basically symmetrical.
In my case it's an Edelbrock intake, heads & valve covers and Holley carb, so the inlet on the carb is on the rear pass. side... only about 8" from the hole in the valve cover. Switching sides means I can eliminate a long hose that routes around in the way of the distributor and where I mounted the ignition module etc. Much cleaner. Not to mention not having to mess w/ that hose every time I want to take the oil cap off.

I assume the oil filler cap/vent all-in-one things are pretty much all the same right?
 
RatLabGuy said:
Roger.
That's what I thought, seeing as the engine is basically symmetrical.
In my case it's an Edelbrock intake, heads & valve covers and Holley carb, so the inlet on the carb is on the rear pass. side... only about 8" from the hole in the valve cover. Switching sides means I can eliminate a long hose that routes around in the way of the distributor and where I mounted the ignition module etc. Much cleaner. Not to mention not having to mess w/ that hose every time I want to take the oil cap off.

I assume the oil filler cap/vent all-in-one things are pretty much all the same right?
Click to expand...
That's fine just make sure whatever oil cap you get is vented and has a filter. Stock there was supposed to be a rubber hose coming off the elbow in the valve cover that ran to a filter in the air cleaner, or to an elbow on the clean side of the carbs filter.
 
Lately about every other hotrod in HR mag. I've seen has about half of a red shop towel zip-tied to a gutted out oil filler cap as a pre-filter. Seems a very good way to monitor and replace as necessary for you have no warning when valve cover filters go bad. Plus cheap! I see no downside to it? I'd imagine a typical "tube sock" would be a good one as well?

I have seen stock oil-fill filters deteriorate from engine heat and become dirt. And you'd never know it.
 
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