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How can I convert Chevy "Script" Valve covers to PCV?

Discussion in 'The Hokey Ass Message Board' started by tradrod, May 2, 2011.

  1. tradrod
    Joined: Jun 28, 2006
    Posts: 171

    tradrod
    Member

    So, I built a SBC and am running "Chevrolet Script" valve covers in my 39 Ford Tudor. These of course do not have a PCV opening. The intake I am using is an old Weiand, without a breather. I drilled a hole in the back of the intake for the PCV valve and put an oil shield on it. I got to thinking about it more and remembered that later SBCs had a breather (routed to air cleaner), on one VC and the PCV on the other. It got me concerned if I had it properly vented, and I was wondering what others have done to solve this problem?

    Thanks in advance

    TR

    Steve
     

    Attached Files:

  2. tradrod
    Joined: Jun 28, 2006
    Posts: 171

    tradrod
    Member

    Sorry fella's, I should have said: without drilling a hole in the top.:)
     
  3. An old intake should have the hole in the front for the oil fill tube or the boss you could drill for the tube. For many years sbc's took air in
    through the fill tube breather and out of the valley through the back of the block via the road draft tube and later by pcv valve. Should still work if your oil baffle is good.
     
    Last edited: May 2, 2011
  4. tmoble
    Joined: Dec 30, 2010
    Posts: 20

    tmoble
    Member

    Yeppers, what he said. Post up a pic of the front of the manifold?
     

  5. Novadude55
    Joined: Nov 10, 2009
    Posts: 2,352

    Novadude55
    Member
    from CA

    If you have a newer style block, post 67 ,, i believe,,
    you wont have the road draft hole next to the distributor hole,
    but earlier blocks have them,, all the small journal motors, 265,283 and 327
    search for 'road draft tube' lots of info here about that,,
    here is one: http://www.jalopyjournal.com/forum/showthread.php?t=92105
     
    Last edited: May 2, 2011
  6. Johnny Gee
    Joined: Dec 3, 2009
    Posts: 9,386

    Johnny Gee
    Member
    from Downey, Ca

    Yes post pic. As said before maybe able to bore boss with 1 1/4" hole. The PCV set up you did I did as well and the fresh air comes via the filler tube with a breather cap. Now as far as valve cover, since all you need to do is have fresh air in. You can come from the side wall with an elbow of some sort. If it was mine I wouldn't do the valve cover thing.
     
  7. ANDEREGG TRIBUTE
    Joined: Jan 1, 2008
    Posts: 1,371

    ANDEREGG TRIBUTE
    Member
    from Bordertown

    What are folks doing for a oil shield under a pcv valve that is tapped into a sbc intake behind the carb in front of the distributor? I want to do this so I can use my vette v/c on my 350 with an old school oil fill tube with a breather cap on the front of the intake, but am stumped on what to do under the intake manifold....thanks
     
  8. tommy
    Joined: Mar 3, 2001
    Posts: 14,757

    tommy
    Member Emeritus

    There must be 6 or 7 complete threads on this subject concerning finned VCs from the 50s. A search using PCV valve and possibly Cal Custom should bring up a lot of ideas to accomplish this. This gets asked every other month.
     
  9. tradrod
    Joined: Jun 28, 2006
    Posts: 171

    tradrod
    Member

    I understand how it was done on early and late SBCs, I thought I would check and see if someone had come up with something "out of the box".

    I did a search, maybe you could help me out with a link?

    Not interested in drilling the tube in the front.
     
  10. ZomBrian
    Joined: Jan 24, 2008
    Posts: 1,143

    ZomBrian
    Member
    from in IN

    Last edited: May 4, 2011
  11. tradrod
    Joined: Jun 28, 2006
    Posts: 171

    tradrod
    Member

    The "tech" article thread is how I fabricated it.

    Of course, however, I drilled the hole in the area of the intake that covers the lifter valley, not the runner:). With a oil shield drilled (and tapped 10/32 bolts) on the "underside" of the intake, respectively.

    But I need to get fresh air for it to be truly "vented" (and please, let's stop getting trivial, I know what PCV is:cool:).

    I'm thinkin' now to drill and tap the front of the intake for a 1/4 pipe thread (not some overkill 1 1/2 " hole :rolleyes:) for a fitting similar to a rear-end vent. I want it functional and well thought out. Just not big and clunky.:D


    Thanks for the links :)
     
  12. R Frederick
    Joined: Mar 30, 2009
    Posts: 2,658

    R Frederick
    Member
    from illinois

    I did this to the intake (behind the carb) on mine.
    [​IMG]
     
  13. tradrod
    Joined: Jun 28, 2006
    Posts: 171

    tradrod
    Member

    Thanks, very similar to what I did, but how do you get air in?
     
  14. blucar
    Joined: Nov 3, 2009
    Posts: 118

    blucar
    Member

    Smog systems, positive crankcase ventilators (PCV's) is possibly one of the most misunderstood subjects there is. Hopefully, to try and simplify things: in order for the PCV system to work you need three things; Fresh air intake, a port into the inner areas of the engine and a vacuum hose with a PCV valve incorporated into the hose from the crankcase/inner portion of the engine.
    If you are working with an engine that has no access into the block like the early 265's 283's and 327's, then you have to tap into the valve covers or the non vacuum portion of the intake manifold. If the intake manifold you are using does not have the early style oil fill tube then the only option is to put a breather into a valve cover on a side away from the port into the push rod chamber of the engine.
    Some people try to use the old valve cover side vents that were used on early aluminum covers, however, they will not work with out a PCV in the system.
    After all is said and done the easiest way to solve the problem would be to deep six the script valve covers in favor of later model covers with baffles and the correct ports for breather and PCV's.
    A second thought is to do nothing about crankcase ventilation, just don't run the engine on the highway.
     
  15. R Frederick
    Joined: Mar 30, 2009
    Posts: 2,658

    R Frederick
    Member
    from illinois

    Oops, I have an oil fill tube intake on mine.
    [​IMG]
     
  16. chop32
    Joined: Oct 13, 2002
    Posts: 1,077

    chop32
    Member

    I like this idea, but Im thinking a normal rear axle vent (the kind with the crimped on cap) wont work, as it is made for letting pressure out, not pulling air in...there must be some sort of air breather out there that isnt "clunky", maybe from a small compressor, or...??
     
  17. 52Poncho
    Joined: Apr 23, 2011
    Posts: 256

    52Poncho
    Member

    No oil tube fill vent then traditional would be a pcv in the manifold and a Mooneyes 90 deg valve cover vent on the inside of the drivers side valve cover behind the generator/alt (carb side not exhaust).
     
  18. tradrod
    Joined: Jun 28, 2006
    Posts: 171

    tradrod
    Member

    Thanks Chop32. I appreciate the clarity Wicked 50. Blucar, read my post #11;)
     
  19. Stevie Nash
    Joined: Oct 24, 2007
    Posts: 2,999

    Stevie Nash
    Member

    Here's mine, pretty simple. Comes out the side instead of the top. Air is coming in through the oil breather / fill tube. If you going to go for the traditiional sbc look, I think you gotta have a oil breather tube...

    [​IMG]
     
  20. ANDEREGG TRIBUTE
    Joined: Jan 1, 2008
    Posts: 1,371

    ANDEREGG TRIBUTE
    Member
    from Bordertown

  21. Topless Ford
    Joined: Feb 10, 2007
    Posts: 560

    Topless Ford
    Member

    Tradrod,
    I may be reading this wrong. It sounds like you wish to use solid valve covers, do not want to use a manifold with a clunky oil fill tube, are running a pcv valve thru-manifold, and wish to allow fresh air in through an axle vent in the manifold.
    I see three problems, one is unfiltered air, two is not enough volume through an axle vent, and finally, are you planning to take of the valve cover each time you wish to add oil?
     
  22. tradrod
    Joined: Jun 28, 2006
    Posts: 171

    tradrod
    Member

    T.F.

    The rear-end vent was just brainstorming, kinda what I was after with this thread. I can add oil through the pcv hole in the intake rear, although not optimal. And if it doesn't use oil, this should be a very small issue.

    I think I can come up with something on the front of the intake to allow more air volume.

    Thanks for reading my posts to try to understand what I am getting at.

    TR
     

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