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Ignorant PCV valve / 5.0 question

Discussion in 'The Hokey Ass Message Board' started by BuiltFerComfort, Jul 2, 2008.

  1. BuiltFerComfort
    Joined: Jan 24, 2007
    Posts: 1,620

    BuiltFerComfort
    Member

    Okay, displaying my ignorance here - I've got what started as a stock '89 Ford 5.0 EFI motor that I've put in a 39 Chrysler. I put a Holley intake and carb and headers on it, plugged the emissions holes in the back of the heads with bolts, got it running. Now I am trying to figure out the PCV valve.

    Basically, do I need to vent the valve covers, and/or run a standard valve-cover-type PCV valve? Or will pulling a vacuum on the oil fill tube be enough?

    At the top of the oil fill tube there is a large nipple to the side for a PCV-sized hose - I can easily run a valve between there and the base of the carb and be done with it. But then I got to thinking about the sealed valve covers (no breathers) and the emissions hose that used to run between the back of the heads. With the rest of the emissions crap removed, will I get undesirable pressure or something in the valve cover area?

    Like I say, ignorance on display. But like my daddy always said, ignorance is curable, while stupidity lasts a lifetime :D.
     
  2. nexxussian
    Joined: Mar 14, 2007
    Posts: 3,240

    nexxussian
    Member

    I found this in the tech archive. I know I have seen other threads on this (in the tech archive too) that have creative ways to do all that.

    If you don't mind an 'open' PCV system (as described in the thread I linked to) you could vent the filler and put the PCV valve into a hole in the valey pan portion of the intake (be careful to make sure you know what part of the intake you are drilling through) as I remember a thread showing how someone did this.

    I even saw a thread somewhere on puting the PCV valve in the lifter valey and plumbing it into the intake from the bottom (on a flathead IIRC, but the idea should work with pushrods, you sould want a baffle in there to keep it from sucking up too much oil though).
     
  3. stillkruzn
    Joined: Apr 10, 2007
    Posts: 981

    stillkruzn
    Member
    from Conway, AR


  4. nexxussian
    Joined: Mar 14, 2007
    Posts: 3,240

    nexxussian
    Member

  5. BuiltFerComfort
    Joined: Jan 24, 2007
    Posts: 1,620

    BuiltFerComfort
    Member

    Thanks - I'm still trying to figure out how fresh air would get into the crankcase. The tech link says "The closed PCV system draws fresh air from the air filter housing." - but I don't know how it would do this the way I have it now.

    I have a big port at the base of the carb (now plugged) that I can use to evacuate the crankcase (via a hose and PCV valve from the oil filler tube)- but where would the air in the 'positive' part of PCV come from? If it's just blowby gasses then I'm cool. If I need some sort of other vent to let air into the crankcase, then I don't think I have it. (Hence this post)
     
  6. nexxussian
    Joined: Mar 14, 2007
    Posts: 3,240

    nexxussian
    Member

    Yes you need another vent, or a tap into the filtered air part of your air filter (I ahve a friend that snuck a hose up to the air filter base and hooked that in for his fresh air inlet, it's between a pair of carbs on a 270 Jimmy, but the same idea).

    If you check C9's post it shows a setup with the fresh air vent hooked to the air filter in the second pic of the engine. That would use a filter in the valve cover cap, or one in the filter housing (one of the white plastic fiber things). I was actually thinking of one that takes air from inside the air filter element through the bottom of the air filter housing (like my buddy W/ the 270 has) so it would work with an open element filter.
     

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