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Old 02-21-2008, 08:38 PM
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valve cover breathers

Is the PVC valve really necessary? I was thinking of putting plain breathers on the valve covers.

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Old 02-21-2008, 08:47 PM
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Yes and no.

Will an engine run without one? Yes. Engines used road draft tubes until the advent of the PCV system.

If you want your engine to last longer, the answer is no. PCV stand for Positive Crankcase Ventilation. Regardless of how good your rings are, some combustion by-product will get by and into the crankcase. These gases will mix with moisture in the air in the crankcase and form acids. Other components will form sludge.

I wouldn't run an engine without one. IMHO, you shouldn't either.
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Old 02-21-2008, 09:54 PM
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Quote:
Originally Posted by sparkyct55
Is the PVC valve really necessary? I was thinking of putting plain breathers on the valve covers.
On a 100% drag motor, it would be fine. On a street motor, I'd follow redsdad's advice.
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Old 02-21-2008, 10:02 PM
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Quote:
Originally Posted by sparkyct55
Is the PVC valve really necessary? I was thinking of putting plain breathers on the valve covers.
just for grins - - - why do you not want to run a pvc
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Old 02-22-2008, 09:05 AM
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This is kinda a yes and no question. A PVC has to have a air supply to the crankcase so yes You could use the valve cover breathers as this supply and have the cool factor. The no side comes in here.These breathers usually don't have any sort of filtering element so it sucks in dirt as well as small dogs. The baffling in side was designed to separate oil from gasses going out not in. The road draft system was prone to sucking oil out at high speeds so it was blocked off and breathers added. The valve cover breathers let the engine find its own pressure equilibrium without a positive scavenging effect.
The only real difference between a road draft system and a PVC is where the end product goes.
Back to the original question. Keep your PVC system operational and install the valve cover breathers for the cool factor Only just drill the mounting holes for them so they dont puke oil all over the top of the engine.
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Old 02-22-2008, 09:21 AM
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Some guys don't like the looks of the p.c.v. and rubber hose on a detailed engine. I always insist on some positive crankcase ventilation, and you can now buy a billet or polished aluminum p.c.v. valve and then plumb it with a 3/8 polished aluminum or stainless line with tiny rubber hose ends. it ends up looking really trick, and the hard line won't deteriorate or lose it's shape. If you do this trick, just use your double-flaring tool, but only do the 1st part of the flare, and you end up with a bubble on the end of the line that will hold the hose tightly!
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Old 02-22-2008, 09:44 AM
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Why does the breather have to be in the valve cover? What about the lifter valley or the timming chain cover? And the pcv valve can be located there to just at the other side or end of engine. TF
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Old 02-22-2008, 10:10 AM
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Quote:
Originally Posted by jaguarxk120
Why does the breather have to be in the valve cover? What about the lifter valley or the timming chain cover? And the pcv valve can be located there to just at the other side or end of engine. TF
yes. Pontiacs had them in the valley cover. baffling is important, at high revs with any blow-by, you don't want to puke out oil.
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Old 02-23-2008, 12:00 PM
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Strictly speaking you need a PCV valve to pass inspection in some states depending on the year of your vehicle.
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Old 02-23-2008, 04:14 PM
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Just wondering when Chevy first came out with the pcv. I have ran a 327 in my 68 Camaro for years without a pvc with no problems.(Probably should have one, but never had a problem without one.)
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Old 02-28-2008, 10:16 PM
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you can put a breather anywhere, or a pcv, the common thing is to have pcv one side valve cover, and the breather filter on the opposit so the fresh air kind of circulates.

i was going to drill my manifold for my pcv/breather/oil fill when i had gm performance valve cover's that were bare with no breather holes, but ended up not using them and getting ones iwth the holes in them.

alot of people run the breathers on the intake manifold with carb LS1 swaps
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Old 02-29-2008, 07:02 AM
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With no breather, and using a PCV valve is it not like using a vacuum pump on the crankcase? TF
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Old 02-29-2008, 07:56 AM
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Quote:
Originally Posted by jaguarxk120
With no breather, and using a PCV valve is it not like using a vacuum pump on the crankcase? TF
in theory yes , but the pump has a load more vacuum.
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Old 03-10-2008, 09:59 PM
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I did not want the pcv. I did not want my chevrolet script valve covers with holes in them either. I bought a eldebrock intake for a quadrajet. Had a machine shop to drill the manifold for a filler pipe and a screw on cap with a pcv drilled in the cap connected to the base vacuum on the carb. When I finished that, and stomped the gas pedal, oil squirted out of my dipstick. The crankcase can build up pressure and blow seals, or however to relieve the pressure. I finally took off my passenger valve cover, drilled a 5/8" hole, welded a nipple pointing towards the carb, got a new air cleaner with a 5/8" nipple under the lower pan of the breather, and added a rubber hose from the valve cover to the bottom of the breather, and it solved all the trouble, no more stinky oil and burning oil on the manifolds. Works great!
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