breather caps vs. PCV
Thread Starter
Burning Brakes
Joined: Nov 2004
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From: San Antonio Texas
breather caps vs. PCV
as a kid my 56 chevy had only breather caps on the valve covers. it wasn't until later that they added the PCV valve and hoses. what are the advantages and disadvantages to just putting breather caps on you street machine? are there any performance gains?
Le Mans Master
Joined: Sep 2000
Posts: 5,635
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From: Orlando Floriduh
If you like breathing oil fumes just run open breathers. The PCV system draws the blowby vapors back into the intake so the engine re burns them. Open breathers work fine when the engine is fresh and tight but as it wears, the vapors begin to get worse.
Last edited by Larry B.; Dec 14, 2004 at 07:24 PM.
Le Mans Master
Joined: Mar 2004
Posts: 7,465
Likes: 1,485
From: Little Rock AR
Yea, what he said. Plus, you will get oil all over the valve covers along with the blow-by gasses that come out of the breathers.
Smokey Yunick did quite a bit of testing on the subject. He ended up piping the two valve covers together with a puke tank/vapor separator in the middle to do the same job without buring the vapors like the factory setup. You can do it too but you will need to fab it up yourself because the parts to do it are kind of expensive to buy off-the-shelf.
Not worth the hassle to me. The factory setup works great and you can tell that it does not cost any power if you do back to back testing at the track with the PCV system blocked vs functional. If you think about it, there isn't any vacuum at WOT to suck anything into the engine so how could it be bad?
I say "if it works, don't fix it".
-Mark.
Smokey Yunick did quite a bit of testing on the subject. He ended up piping the two valve covers together with a puke tank/vapor separator in the middle to do the same job without buring the vapors like the factory setup. You can do it too but you will need to fab it up yourself because the parts to do it are kind of expensive to buy off-the-shelf.
Not worth the hassle to me. The factory setup works great and you can tell that it does not cost any power if you do back to back testing at the track with the PCV system blocked vs functional. If you think about it, there isn't any vacuum at WOT to suck anything into the engine so how could it be bad?
I say "if it works, don't fix it".-Mark.
Race Director
Joined: Feb 1999
Posts: 19,659
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From: Lenoir City Tennessee
Ci 6, 8 & 10 Veteran
St. Jude Donor '05-'06-'07-'08-'09-'10-'11-'12-'13-'14-'15
I have a breather on one side and a PCV valve on the other side. Both are in billet aluminum by Zoops. This part about the car I kept stock.
Melting Slicks
Joined: Apr 1999
Posts: 2,010
Likes: 3
From: Moon Twp. PA USA
Originally Posted by greyghost79
as a kid my 56 chevy had only breather caps on the valve covers. it wasn't until later that they added the PCV valve and hoses. what are the advantages and disadvantages to just putting breather caps on you street machine? are there any performance gains?
Race Director
Joined: Sep 1999
Posts: 11,360
Likes: 382
From: Plano TX
I ran with the PCV system disconnected for awhile and I think there wasn't a seal that didn't leak. Valvecovers, intake, even the distributor seal leaked. Always had drips coming off the oil pan. Reconnected PCV and all the leaks stopped just like that. Doesn't leak a drop anymore.
