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PCV Valve, Do I need to use one?

mpro69rr

mpro69rr

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Hey Guys,

I have a 69 RR 383 and was wondering if I have to use a PCV valve (mine came with one)or would a breather be fine on both valve covers. I'v seen people who don't use them and some who do. Why do you need one if a breather will let the air out?
 
A PVC system keeps the rings in better condition, keeps the inside cleaner, and may lessen oil leaks. Best to find the correct grommets and run one.
 
Demonic said:
A PVC system keeps the rings in better condition, keeps the inside cleaner, and may lessen oil leaks. Best to find the correct grommets and run one.
Click to expand...

That's interesting, never heard that before. I think I will run one to be on the safe side, my engine just got rebuilt. I already have the grommet for it.
 
mpro69rr said:
That's interesting, never heard that before. I think I will run one to be on the safe side, my engine just got rebuilt. I already have the grommet for it.
Click to expand...
Just make sure your valve cover has a baffle in it where the valve goes.
 
What cam are you running? And what vacuum readings do you have at idle?
Reason asking is that if you run a "wild" cam and have low vacuum you are better off using the Wagner adjustable PCV valve.
But if it is a stock-ish type rebuild, a standard PCV valve will do.
 
Wietse said:
What cam are you running? And what vacuum readings do you have at idle?
Reason asking is that if you run a "wild" cam and have low vacuum you are better off using the Wagner adjustable PCV valve.
But if it is a stock-ish type rebuild, a standard PCV valve will do.
Click to expand...

I haven't put the engine in yet so its not running, its not a mild build but its not radical has about 400-450 HP at the crank. I'll look into the wagner, what is the difference and how do you use an adjustable?
 
A standard PCV valve has 2 pre-set flow settings.
One is for idle, and once the vacuum increases the 2nd stage kicks in to allow more air in during cruising.
The Wagner PCV valve is adjustable for both settings and you can tailor it to suit your engine, against a solid price though.
I am using one and it works really well, but if you have a mild build and decent vacuum and are able to set the idle and cruise mixtures with a standard PCV valve you do not really require the Wagner valve.
 
mpro69rr said:
Hey Guys,

I have a 69 RR 383 and was wondering if I have to use a PCV valve (mine came with one)or would a breather be fine on both valve covers. I'v seen people who don't use them and some who do. Why do you need one if a breather will let the air out?
Click to expand...
Yes you need one in one valve cover plumbed to the base of the carb and a vented cap on the other valve cover. The vented/fill cap may be connected to the air cleaner depending on year and model. Fresh air in one side, through the engine and out the other through the pcv and into the carb/engine.
 
Last edited:
mpro69rr said:
Why do you need one if a breather will let the air out?
Click to expand...
Because that is a "ventilated" crankcase, but NOT a "positive ventilated"crankcase. Think of it like cracking the window on your car an inch or so. You'll get some ventilation, but not much, but if you turn on the blower, you get "positive ventilation", which is MUCH more effective. I wouldn't run without one.
 
toolmanmike said:
Yes you need one in one valve cover plumbed to the base of the carb and a vented cap on the other valve cover. The vented/fill cap may be connected to the air cleaner depending on year and model. Fresh air in one side, through the engine and out the other through the pcv and into the carb/engine.
Click to expand...



the positive crank case valve removes fumes like oil / fuel and moisture form the engine. way back engines would blow off oil pans with out a p c v valve. do you thing you need one ????
 
I've always thought of it this way... a motor is a big air pump, typically were more focused on what's happening inside the cylinder with valve open/closing timing. The other side of those piston are pumping air as well with a lot less ability to tune it... Another reason racers run evacuation systems.
 
So the old road draft tubes went away in about 1962 or so. The PCV systems then went into operation. Why would you want to re-engineer the working technology and go back to the old ways of the 1950s that didn't work as well?
 
I'm glad I read threw this I never gave much thought to a pcv valve always used to toss them to put a breather on (chrome was shinny) never thought it was a bad thing whoops. In working in the diesel field never really learned about them!
Thanks for info guys I'm sure op learned some to !
 
Bb70charger500 said:
I'm glad I read threw this I never gave much thought to a pcv valve always used to toss them to put a breather on (chrome was shinny) never thought it was a bad thing whoops. In working in the diesel field never really learned about them!
Thanks for info guys I'm sure op learned some to !
Click to expand...

diesel don't make vacuum so it is hard to keep there crank case vented. some light trucks made buy Detroit had vacuum pumps installed as they idle in traffic to long.
 
Bb70charger500 said:
I'm glad I read threw this I never gave much thought to a pcv valve always used to toss them to put a breather on (chrome was shinny) never thought it was a bad thing whoops. In working in the diesel field never really learned about them!
Thanks for info guys I'm sure op learned some to !
Click to expand...

Yes, I learned a lot too, never thought it was so important! Thanks Guys!
 
I use one that fits in a breather and have another breather on the other side. also run the pcv through a catch can then back to the carb. works great!

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The first engine I ever built and knew nothing I just put a breather in one valve cover, blew the intake end seals on a SB Chevy, replaced it and blew it again, added a PVC along with the breather and never lost another drop of oil. I've always ran a breather on one valve cover and a PVC valve on the opposing cover ever since and have never had a problem since.
 
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