PCV breather cap question
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Elder User
Joined: Jul 2003
Posts: 586
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From: South Dakota
PCV breather cap question
Ok The PCV connected to a plate underneath my 2 bbl carb and this is basically an emissions thing it feeds the vapor into the engine to be burned up right?
So with the 4 bbl on it and I switch to the breather caps with no hoses attached to them will this hurt anything?
I was wondering because I can see vapor coming from the breather cap?
So with the 4 bbl on it and I switch to the breather caps with no hoses attached to them will this hurt anything?
I was wondering because I can see vapor coming from the breather cap?
Postmaster
Joined: Feb 2003
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For the PCV system to work, air has to flow through the engine. It is preferable that the air is filtered before it enters the crankcase. The FE has the breather cap on the drivers side valve cover. That is the intake for the PCV system. Filtered air is drawn from the air cleaner assembly into the crankcase. This air is pulled through the crankcase and out the pcv valve on the passenger side valve cover. The crankcase gases are then drawn into the intake and burned. For the system to work , the air has to flow. If you replace the oil fill cap or air cleaner assembly, us a cap that has filtering ability.
If you remove the pcv valve and just use breather caps on both sides, it's not good for the engine. You shouldn't have pressure building in the engine because the 2 breathers should allow the gasses to escape readily enough. But the gases that are in the crankcase can be corrosive. Without the PCV system, those gases can linger and not be drawn out of the engine.
If you remove the pcv valve and just use breather caps on both sides, it's not good for the engine. You shouldn't have pressure building in the engine because the 2 breathers should allow the gasses to escape readily enough. But the gases that are in the crankcase can be corrosive. Without the PCV system, those gases can linger and not be drawn out of the engine.
Posting Guru
Joined: Sep 2003
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From: lino lakes, mn
your engine is an air pump pistons going down create pressure in the crankcase pcv stands for POSITIVE crankase ventilation it sucks the air out of your cankcase it is not an emissions thing you will blow the seals out of your crankcase it does not hurt perfomance it will actually help it by relieving crankcase back pressure
Cargo Master
Joined: Apr 2004
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From: Golden, CO
Originally Posted by plowpusher
your engine is an air pump pistons going down create pressure in the crankcase pcv stands for POSITIVE crankase ventilation it sucks the air out of your cankcase it is not an emissions thing you will blow the seals out of your crankcase it does not hurt perfomance it will actually help it by relieving crankcase back pressure
Post Fiend
Joined: Mar 2004
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From: Union, Washington
Originally Posted by plowpusher
your engine is an air pump pistons going down create pressure in the crankcase pcv stands for POSITIVE crankase ventilation it sucks the air out of your cankcase it is not an emissions thing you will blow the seals out of your crankcase it does not hurt perfomance it will actually help it by relieving crankcase back pressure
The pressure in the crankcase is created by blowby past the piston rings, (not the pistons going up and down as everytime a piston comes down another is going up, equalizing the volume in the crankcase) which cause the pressure to escape thru the road draft tube in the old days, down under the car onto the road. And yes, the PCV system is an emissions thing because they want the engine to burn this stuff and not dump it onto the road and into the atmosphere. The PCV system has nothing to do with improving preformance. And no you will not blow any seals unless you have less than enough vents. If he uses the vents on the valve covers only, without PCV system, then he will blow crap all over his valve covers. Run the PCV system with the 4 barrel, there will be a port for the system to hook to on the carb or the spacer.
Lead Driver
Joined: Sep 2003
Posts: 5,844
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From: Albuquerque
Originally Posted by Bear 45/70
The pressure in the crankcase is created by blowby past the piston rings, (not the pistons going up and down as everytime a piston comes down another is going up, equalizing the volume in the crankcase) which cause the pressure to escape thru the road draft tube in the old days, down under the car onto the road. And yes, the PCV system is an emissions thing because they want the engine to burn this stuff and not dump it onto the road and into the atmosphere. The PCV system has nothing to do with improving preformance. And no you will not blow any seals unless you have less than enough vents. If he uses the vents on the valve covers only, without PCV system, then he will blow crap all over his valve covers. Run the PCV system with the 4 barrel, there will be a port for the system to hook to on the carb or the spacer.
Thanks!
biz
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Post Fiend
Joined: Mar 2004
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From: Union, Washington
Originally Posted by biz4two
That's good info Bear! But what about the other side where the oil cap is? Is it necessary to connect oil cap to the air cleaner? Or is it possible to only have the PCV system connected as you suggested and have the oil cap vent into the atmosphere?
Thanks!
biz
Thanks!
biz
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Postmaster
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Originally Posted by biz4two
That's good info Bear! But what about the other side where the oil cap is? Is it necessary to connect oil cap to the air cleaner? Or is it possible to only have the PCV system connected as you suggested and have the oil cap vent into the atmosphere?
Thanks!
biz
Thanks!
biz
Post Fiend
Joined: Mar 2004
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From: Union, Washington
Originally Posted by 76supercab2
You could do that but you will be drawing unfiltered air into the crankcase.
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Post Fiend
Joined: Dec 2003
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From: "Islander"
On the 68-69 FE trucks the air for the valve cover comes off a 90 degree pipe stub on the outside of the air filter housing which is unfiltered air. The stainless steel "Brillo" material inside the left and right filler cap needs to be cleaned once a year as well the PCV valve. Soak in a gallon can of Berrymann's carb cleaner, rinse then repaint outside. I added another 90 degree stub on the inside of the air filter housing then connected a filter so the motor gets clean dust free air inside.
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Freshman User
Joined: Feb 2004
Posts: 31
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From: Olympia, WA
No holes in Valve Covers
I am building a 406 with a Blue Thunder single 4barrel intake. I have no valve cover holes. It sounds like using a PVC on the rear somehow and the oil fill cap as the intake filter is the proper method?
Post Fiend
Joined: Dec 2003
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From: "Islander"
If you have cast aluminum covers they should have plugs that you knock out for PCV and oil fill, that's what a set of Mickey Thompson covers I have. Older Cal-Custom covers came with the holes when new.
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Postmaster
Joined: Feb 2003
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Originally Posted by Beemer Nut
On the 68-69 FE trucks the air for the valve cover comes off a 90 degree pipe stub on the outside of the air filter housing which is unfiltered air.
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http://www.autozone.com/servlet/UiBr...ction=loadPage
Assuming that they have the correct part listed.
Senior User
Joined: Sep 2005
Posts: 359
Likes: 1
From: Saint Paul, MN
PVC system
snoopypup,
That will work. My 304 (Jeep) has a PVC valve in the rear of the intake, a tube in front of the intake to fill oil and no holes in the valve covers.
That will work. My 304 (Jeep) has a PVC valve in the rear of the intake, a tube in front of the intake to fill oil and no holes in the valve covers.
Last edited by tomcasino; Sep 27, 2005 at 12:40 AM. Reason: Forgot words