Valve cover plumbing question

Discussion in 'High Tech Retrofits' started by AlexSpinn, Dec 20, 2017.

  1. AlexSpinn

    AlexSpinn New Member

    Jan 31, 2017
    10F24606-6F17-416D-8014-141046FF2C66.jpeg F603F013-85F5-41E8-8944-A947AB6B7D93.jpeg Just wondering where you guys plumb these tubes coming out of valve covers. Do they just need to be hooked up to a constant vacuum?
  2. LoweRider

    LoweRider Member

    Jun 26, 2017
    TX, USA
    IIRC, that's for PCV. you can run a catch can between that and the throttle body
  3. SRGN

    SRGN Veteran Member

    Feb 20, 2009
    Central NJ
    The one pic is the pcv valve. Goes to constant vacuum. The capped one is the vent and is normally routed to the air intake plumbing before the throttle body. Some people install a breather there, either way it shouldn't be capped.
  4. badazz81z28

    badazz81z28 Veteran Member

    May 4, 2001
    Las Vegas, NV
    They are both PVC fresh air inlets. They can be both tapped together and plumbed to the air intake AFTER the MAF. Many cases people cap off the driver side and just run the passenger side to the intake.

    Don't put a "breather" there and allow it to suck un-measured air on a MAF EFI engine. Some people do put a sealed catch-can inline with the PCV but between the valley cover and the intake, not the rocker arm cover.

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