Valve cover vent tube...... Reply #15 – January 27, 2013, 01:37:55 PM The Motorsport tall covers allow for a baffle and they come with one but it is not installed when you get them. Short answer is yes. I cannot vent the driver side due to the upper intake being too close. Darren Quote Selected
Valve cover vent tube...... Reply #16 – January 27, 2013, 02:14:20 PM I always cap it but don't vent it if you vent it your PVC will just pull air in through it ....very little bit it is considerd a vacuume leek I only run breathers on the race car because the PVC pulls gobs of oil through the intake When money allows ill go with a vacuume pump Quote Selected
Valve cover vent tube...... Reply #17 – January 27, 2013, 03:43:33 PM The valve cover vent is to let filtered air from the throttle body in. Not to let fumes out.The question is, with no vent will the PCV pull too high a vacuum in the crankcase? Is that a problem? Quote Selected
Valve cover vent tube...... Reply #18 – January 27, 2013, 06:01:35 PM You really think filtered air is going to go through that tube against engine vacuum in the throttle body? Quote Selected
Valve cover vent tube...... Reply #19 – January 27, 2013, 07:22:15 PM Quote from: 88turbo;408179You really think filtered air is going to go through that tube against engine vacuum in the throttle body? Yep. That is how it works. Air goes in through the valve cover and out the through the PCV. Quote Selected
Valve cover vent tube...... Reply #20 – January 27, 2013, 10:14:22 PM Its been that way on my car for over ten years so I guess you could say it works...Darren Quote Selected
Valve cover vent tube...... Reply #21 – January 27, 2013, 11:05:47 PM I may cap my valve cover and throttle body and test it out. I appreciate the replies. Quote Selected
Valve cover vent tube...... Reply #22 – January 27, 2013, 11:56:10 PM caping off the valve cover fitting just kinda reminds me of offering a situation where you "could" possibly suck in your valve cover or oil pan gasket, without a way for fresh air to get in and your intake is constantly sucking pressure ,, dono, may just be me but it kinda feels odd... cant exactly put my finger on it but if the crankcase cant circulate , somethings gotta give.thank goodness none of us seem to run those lousy rubber valve cover gasekets anymore.......... or do we. Quote Selected
Valve cover vent tube...... Reply #23 – January 28, 2013, 12:05:59 AM Quote from: softtouch;408184Yep. That is how it works. Air goes in through the valve cover and out the through the PCV. wrong, the air is sucked OUT of the valve cover and into the throttle body. if air goes INTO the valve cover it blows your dipstick out and sprays oil out it. why do you think you have to cap the end at the throttle body and run a hose from the valve cover to after the mass air sensor but infront of the inlet side of a supercharger when you install one? (in other words, the suction end of the blower, if you dont do this, the dipstick thing happens as you are adding air, rather then removing it like the factory designed.) plus if you just leave it off, with a mass air car, that is un metered air (vaccum leak.) going into your engine which will throw off your air fuel ratio's. and make it run like a bag of shiznit.this is one of those BS filled threads that i cant believe people are saying to just remove that tube and it will be good. wow. Quote Selected
Valve cover vent tube...... Reply #25 – January 28, 2013, 06:47:16 AM Hmmmmmm....I may just work the tube in somewhere then. Quote Selected
Valve cover vent tube...... Reply #26 – January 28, 2013, 08:12:42 AM I've read about that problem with mass air and just capping that tube...just guessing here, that a stock motor wouldn't care either way then Quote Selected
Valve cover vent tube...... Reply #27 – January 28, 2013, 08:53:26 AM That tubes purpose it to allow the pcv system to pull already filtered air from the intake, through the crank case. The air is then drawn through the pcv valve on the intake manifold. This is possible because manifold vacuum ranges from 20in. to about 0in depending on throttle position, while vacuum in the intake duct stays around 0in all the time. You can certainly eliminate that tube by capping it at the throttle body and adding a breather filter to the valve cover. Making this change is a necessity for anyone running a turbo or supercharger. Quote Selected
Valve cover vent tube...... Reply #28 – January 28, 2013, 10:24:31 AM Quote from: 1WLD BRD;408223wrong, the air is sucked OUT of the valve cover and into the throttle body. if air goes INTO the valve cover it blows your dipstick out and sprays oil out it. why do you think you have to cap the end at the throttle body and run a hose from the valve cover to after the mass air sensor but infront of the inlet side of a supercharger when you install one? (in other words, the suction end of the blower, if you dont do this, the dipstick thing happens as you are adding air, rather then removing it like the factory designed.) plus if you just leave it off, with a mass air car, that is un metered air (vaccum leak.) going into your engine which will throw off your air fuel ratio's. and make it run like a bag of shiznit.this is one of those BS filled threads that i cant believe people are saying to just remove that tube and it will be good. wow. if you look at it closely and think it through, you'll probably agree that the tube section is bi directional depending on the available vac suction at the upper intake..just check me here......-at lower rpms or idle dominant vac pressure exists at the intake to generate the air moving machine so to speak,,,, so, air flows from the crank case, then through the spark arrestor, then through the pcv, then through the upper intake vac dist tree, then through the intake, then to the pistons. IT would make sense during this situation that fresh outside air must come into the trottle body, then in through the black plastic tube then down the valve cover kneck and to the crank case.-at high rpms, the same should happen but the dominant vac presure now moves to the throttle body at the plastic tube fitting due to the volume of air passing by the fitting. Air should move from the crank case and into the tb but i have no idea how air is getting "into" the crank case because the pcv is a one way check valve and should be closed. perhaps the this is when the center hole on the upper / low comes in play...and i may have answered my own question.this may be another reason why there is no check valve on the plastic tube if you think about it.on the CFI cars 5.0 or 3.8, the pcv had two hose connectoins and one goes to the air cleaner , same operaton as above just a different layout.ive always considered the tube as bi directonal so thats why i was saying the TB could be capped but not the valve cover neck.thoughts? Quote Selected
Valve cover vent tube...... Reply #29 – January 28, 2013, 01:20:43 PM Quote from: 1WLD BRD;408223wrong, the air is sucked OUT of the valve cover and into the throttle body. if air goes INTO the valve cover it blows your dipstick out and sprays oil out it. why do you think you have to cap the end at the throttle body and run a hose from the valve cover to after the mass air sensor but infront of the inlet side of a supercharger when you install one? (in other words, the suction end of the blower, if you dont do this, the dipstick thing happens as you are adding air, rather then removing it like the factory designed.) plus if you just leave it off, with a mass air car, that is un metered air (vaccum leak.) going into your engine which will throw off your air fuel ratio's. and make it run like a bag of shiznit.this is one of those BS filled threads that i cant believe people are saying to just remove that tube and it will be good. wow.I don't know about super charged or turbo systems, but that is not what we are talking about. If the intake is pressurized I can see where you would not have any intake manafold vacuum.The vacuum on the PCV is sucking the crankcase fumes out and this draws the air into the valve cover vent.If the blowby is more than the PCV can suck out, then it will go out the valve cover vent.In the 60's they vented to the air.That's why they put the tube to the throttle body to keep the fumes from venting to the air.The throttle body is not sucking the fumes. The pressure in the crankcase is pushing the fumes if there high blowby.So the BS is flowing from Dunnville, along with the cold air. Quote Selected
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