Crankcase Breathers Necessary?
Thread Starter
Melting Slicks
Joined: Sep 2004
Posts: 2,412
Likes: 3
Crankcase Breathers Necessary?
All of the valve covers that I'm looking at don't come with breather provisions. So I have two questions:
First, do I need breathers? Will so much pressure build up that I'll develop oil leaks everywhere?
Second, most valve covers have these metal devices underneath the cover that prevents oil from splashing up into the breather. Obviously my new covers will not have these. If I simply drill a 1 1/4" hole and push the breathers in will they be ok? Or will too much oil come up from underneath?
First, do I need breathers? Will so much pressure build up that I'll develop oil leaks everywhere?
Second, most valve covers have these metal devices underneath the cover that prevents oil from splashing up into the breather. Obviously my new covers will not have these. If I simply drill a 1 1/4" hole and push the breathers in will they be ok? Or will too much oil come up from underneath?
Burning Brakes
Joined: Aug 2005
Posts: 1,126
Likes: 0
From: Hudson Falls, N.Y. 76 Vette Modified L-48
First...where's your PVC valve connected to (if the car has one)? My 76 is in the driver side cover..when I took my PVC (temporarily) out, I had oil coming out all over the chrome cover parts, chrome breather and chrome filler tube...I'd say...yes, you need to have a breather to pull the crank gases...but a vacuum PVC valve would work better..there must be a cover you can buy with a PVC hole..
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,445
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
It's time to start thinking outside the box! At some point you can't always ask questions. You have to decide some things on your own.
First ask yourself. Why is somebody buying these cast valve covers without breathers or PVC? Simple answer they are for custom hot rod motors and no two are alike!
Custom means you make the decision. You get the hole saw, breathers, rubber gromets, and PVC. Then you make the decision on where you want them and how many.
First ask yourself. Why is somebody buying these cast valve covers without breathers or PVC? Simple answer they are for custom hot rod motors and no two are alike!
Custom means you make the decision. You get the hole saw, breathers, rubber gromets, and PVC. Then you make the decision on where you want them and how many.
Thread Starter
Melting Slicks
Joined: Sep 2004
Posts: 2,412
Likes: 3
Originally Posted by gkull
It's time to start thinking outside the box! At some point you can't always ask questions. You have to decide some things on your own.
First ask yourself. Why is somebody buying these cast valve covers without breathers or PVC? Simple answer they are for custom hot rod motors and no two are alike!
Custom means you make the decision. You get the hole saw, breathers, rubber gromets, and PVC. Then you make the decision on where you want them and how many.
First ask yourself. Why is somebody buying these cast valve covers without breathers or PVC? Simple answer they are for custom hot rod motors and no two are alike!
Custom means you make the decision. You get the hole saw, breathers, rubber gromets, and PVC. Then you make the decision on where you want them and how many.
But I wanted to get opinions before I bought another set of valve covers that everyone hated. My covers now are kinda tacky, they call for hydraulics and 12" gold wire spoke rims.
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Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,445
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
Sorry that I was a little harsh. Breathers raise HP and actually if you go up to vacuum pumps or dry sump sytems you'll see even more free power.
I originally had a K&N filter breather on my drivers side cover. I changed it over to a air cleaner breather. The PVC is drilled into the rear intake manifold side.
I'm running the bigger crane gold stud girdle so it blocks the oil spash.
Not a good picture, but this is one of my older motors with a mech. fan.
I originally had a K&N filter breather on my drivers side cover. I changed it over to a air cleaner breather. The PVC is drilled into the rear intake manifold side.
I'm running the bigger crane gold stud girdle so it blocks the oil spash.
Not a good picture, but this is one of my older motors with a mech. fan.
Safety Car
Joined: Jun 2004
Posts: 4,652
Likes: 80
From: Lakeland Florida
I heard that if you dont have any type of breathers/PVC system on your valve covers that the internal pressure will build up enough to cause leaks from the pressure.
Having said that, if you dont have holes in your valve covers, then how do you add oil?
And last...didnt early Chevy V-8 engines have some type of external oil filler tube at the front of the engine which meant those valve covers may not have needed holes in them, but they did have an oil filler tube.
kdf
Having said that, if you dont have holes in your valve covers, then how do you add oil?
And last...didnt early Chevy V-8 engines have some type of external oil filler tube at the front of the engine which meant those valve covers may not have needed holes in them, but they did have an oil filler tube.
kdf
Thread Starter
Melting Slicks
Joined: Sep 2004
Posts: 2,412
Likes: 3
Originally Posted by gkull
Sorry that I was a little harsh. Breathers raise HP and actually if you go up to vacuum pumps or dry sump sytems you'll see even more free power.
I originally had a K&N filter breather on my drivers side cover. I changed it over to a air cleaner breather. The PVC is drilled into the rear intake manifold side.
I'm running the bigger crane gold stud girdle so it blocks the oil spash.
Not a good picture, but this is one of my older motors with a mech. fan.
I originally had a K&N filter breather on my drivers side cover. I changed it over to a air cleaner breather. The PVC is drilled into the rear intake manifold side.
I'm running the bigger crane gold stud girdle so it blocks the oil spash.
Not a good picture, but this is one of my older motors with a mech. fan.
But if you don't have a stud girdle, how badly will the oil splash? Or someone just convince me to get a stud girdle.
Last edited by enkeivette; Dec 6, 2005 at 09:22 PM.
Thread Starter
Melting Slicks
Joined: Sep 2004
Posts: 2,412
Likes: 3
Originally Posted by Redshark6974
the oil will splash really bad..i had cast valve covers on my old 383, no baffles...oil was everywhere...added the baffles, and its ok now.
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,445
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
Way back I ran K&N filter type breathers and I bought spun stainless steel scrub pads and cut a piece of it off and stuffed it up in the tube and filter because the splash always kept the filter wet. It cured the problem
You can also see where I put the PVC on the side is in between the cylinders. So it's away from the valve springs.
You see the Weiand manifold came with tapped 3/8ths fitting to put my PVC to
You can also see where I put the PVC on the side is in between the cylinders. So it's away from the valve springs.
You see the Weiand manifold came with tapped 3/8ths fitting to put my PVC to
Race Director
Joined: Nov 1999
Posts: 10,643
Likes: 8
From: Foxfield CO 1970 Convertible
Originally Posted by torqvette
Hmmm... who sells the baffles and how are they installed? I'm assuming they'd need to be welded in. It would not be good if one of those fell down.
Race Director
Joined: Nov 1999
Posts: 10,643
Likes: 8
From: Foxfield CO 1970 Convertible
Originally Posted by kdf1986
Having said that, if you dont have holes in your valve covers, then how do you add oil?
Last edited by Z-man; Dec 7, 2005 at 11:10 AM.
Le Mans Master
Joined: Apr 2000
Posts: 5,202
Likes: 10
From: cincinnati ohio
St. Jude Donor '09
Who says you have to put the PCV valve in the valve covers? On my last few manifolds I've drilled my intakes over the lifter valley for the valve. When I got these trick new covers the last thing I wanted was a bunch of crap hanging out of the top of them. Crankcase air intake is on the back of one cover plumbed to the air cleaner assembly. I did fab a baffle under the grommet in the intake and I used a lifter valley baffle. 
