venting of valve covers

Discussion in 'Engine Topic' started by Mr_Z27, Mar 26, 2007.

  1. Mr_Z27

    Mr_Z27 Veteran Member

    Dec 7, 1999
    Sioux Falls, SD
    Should you run the pcv valve in one valve cover and an air breather in the other or should the other valve cover stay sealed. I do not have any other type of vent or breather such as the old style filler stack off the front of the intake.
  2. jakeshoe

    jakeshoe Veteran Member Lifetime Gold Member

    Dec 8, 2000
    Republic of Texas
    For the PCV to be effective there must be a vent, so yes a vent in the opposite valve cover is the best solution.
  3. Levi

    Levi Guest

    Yeah, engine has to breathe and exhale man. Atleast you dont have to use your EGR right?
  4. Nate81camaro

    Nate81camaro Veteran Member

    Jun 3, 2006
    I should probably get around to putting a pcv valve in. Does it hurt the engine if I'm running a breather on both sides? Sorry for the NEWB question.
  5. zekefreak

    zekefreak Veteran Member Lifetime Gold Member

    Apr 16, 2006
    western PA
    By not running a pcv, blow-by gases will eventually contaminate the oil and then you could be asking for trouble.
  6. My81Z28

    My81Z28 Member

    May 2, 2006
    Nova Scotia, Canada
    I am interested to know the answer to this one. My valve covers have 2 holes each in them. I use 1 for PCV, 1 for oil cover, and the other 2 (1 on each side) for breathers. Why does pcv have to be hooked up to carb ???
  7. Rick WI

    Rick WI Veteran Member

    Jul 9, 2001
    Madison, WI
    Not sure how you figure that?
  8. Charlie Brengun

    Charlie Brengun Veteran Member Lifetime Gold Member

    Feb 24, 2002
    the Netherlands
  9. zekefreak

    zekefreak Veteran Member Lifetime Gold Member

    Apr 16, 2006
    western PA
    The pcv is hooked to the carb for a vacuum source. This sucks out the air inside the engine drawing all the gases with it and reburns them in the combustion chamber. A breather on each side would be less efficient as it would draw air from the nearer breather and not the air inside the engine. You should block off the extra hole on the pcv side and use only the breather on the other side. The oil cover should seal tight and not allow air to enter. Also, VERY IMPORTANT!! Make sure the oil drain holes in the heads are open and not gunked up as this affects the pcv system, not to mention all the excess oil in the valve covers.

    ps. Thanks Charlie!
    Last edited: Mar 26, 2007
  10. tomsti

    tomsti Veteran Member

    Jul 15, 2003
    Redmond, Wa, USA
    I have two breathers and have run that way on other engines. May need to rethink this...

    Question, at what point do big cams effect the functionality of a PVC system? If it operates on vacuum some cams will not pull very effectively. Assuming that the normal street engine operating range is going to be lower RPM.

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