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My PCV valve install in SBC intake

Discussion in 'The Hokey Ass Message Board' started by oldrelics, Sep 12, 2010.

  1. oldrelics
    Joined: Apr 7, 2008
    Posts: 1,728

    oldrelics
    Member
    from Calgary

    This is how I added my PCV valve in the intake so I could run no holed valve covers.

    Cut out a SBC chev valve cover PCV baffle:
    [​IMG]

    I am not using this mount pedestal so I cut it off, left 3/4 inch standing.
    [​IMG]

    Drill it out for the correct size for 3/8 NPT and tap it.
    [​IMG]

    Shape the metal on the baffle to fit between the ribs and drill small 10-32
    holes.
    [​IMG]
    [​IMG]
    [​IMG]

    Seal the PCV baffle to intake.
    [​IMG]

    Thread and screw the PCV baffle to underside.
    [​IMG]

    Peen over sheetmetal and tack weld screws so they can never fall.
    [​IMG]

    Finished.
    [​IMG]
    [​IMG]
    [​IMG]

    The PCV valve is for newer Nissans, it is steel.
    The fresh air draws in from the oil fill tube on the front of the engine.

    Here is the tube that is in the plenum. It has a 1/8 in hole facing down just before the pinch. The tube being in the center allows to mix evenly with the fuel mixture. Just connect the nipple to the pcv with a 3/8 hose.
    [​IMG]
     
    Last edited: Aug 17, 2011
  2. Merlin
    Joined: Apr 9, 2005
    Posts: 2,546

    Merlin
    Member
    from Inman, SC

    Nicely done!
     
  3. That's a darn good idea! Nice work.
     
  4. canman
    Joined: May 6, 2010
    Posts: 112

    canman
    Member

    Nice job. Can't think why it would not work?
     

  5. ROBERT JAM
    Joined: Nov 13, 2002
    Posts: 1,201

    ROBERT JAM
    Member

  6. djust
    Joined: May 31, 2006
    Posts: 1,230

    djust
    Member
    from Oklahoma

    I drilled my intake and threaded the hole so I could hard pipe the pcv valve into the riser of my back carb.
    Car is not driving yet just started it a few times to set the timing and fix a few leaks but notice the pcv valve is 2 pieces that rotate inside each other and it is dripping some oil so maybe it is picking up to much splash from under the intake.
    I need to put a baffle under there like yours.
    Thanks for the idea.
     
  7. gimpyshotrods
    Joined: May 20, 2009
    Posts: 17,671

    gimpyshotrods
    ALLIANCE MEMBER

    It will work just fine. There are a fair number of us here who run our PCV valves just like that, or something very similar. I run a baffled grommet and a conventional SBC PCV valve in mine.

    The topic comes up just about every 1/2 year or so. So far, I have yet to have any trouble, or hear of any trouble from anyone who is actually running this setup.
     
  8. Von Rigg Fink
    Joined: Jun 11, 2007
    Posts: 13,428

    Von Rigg Fink
    Member
    from Garage

    I ran into a simular problem when my PCV was sucking off the back side of my 1st out of 3 , 2gc rochesters..it starved the #1 cyl when it came time for it to suck fuel it sucked crankcase and ended up at low RPM with a dead cyl.

    central placement is key
     
  9. pecker head
    Joined: Nov 8, 2006
    Posts: 3,768

    pecker head
    Member

    I did the same thing on my sedan , 2 weeks later , I put a aluminum sheild over the valve cover baffle that I put in. There is a hell of a oil hurracane going on under their . It worked great after that . There are a lot of threads on this subject !
     
  10. lorodz
    Joined: Jul 26, 2009
    Posts: 3,728

    lorodz
    Member

    lets see the finished result ..
     
  11. Very nice. I have also done same thing in that same location. May I suggest a 45 degree burbed fitting instead of the straight that you are useing. I also tap the back of carb (Holley) to receive a 45 degree fitting. The alignment is perfect that way with no kinks.
     
  12. lorodz
    Joined: Jul 26, 2009
    Posts: 3,728

    lorodz
    Member


    your so talented...lol...lets see it ...
     
  13. 39 Ford
    Joined: Jan 22, 2006
    Posts: 1,558

    39 Ford
    Member

    I did the same thing on my small block, took the manifold with carb to the local NAPA store and found a pre-bent hose and fitting to make it look "factory".
     
  14. JAWS
    Joined: Jul 22, 2005
    Posts: 1,846

    JAWS
    Member

    Run it into the bottom of the air cleaner. It still pulls vac there and won't mess up your tune.
     
  15. Brad54
    Joined: Apr 15, 2004
    Posts: 6,012

    Brad54
    Member
    from Atl Ga

    That's what I did.
    I ran a PCV from the carb to the sealed oil fill tube, just like the factory closed-system cars for California in '62.
    Then I ran a port from the back of the intake (nearly the same location as the one shown) to a port on the underside of my open-element air cleaner base.

    32,000 miles, and I've only had two issues: The first was the PCV valve flowed the wrong direction, so my air cleaner base filled up with oil. PCV valves are directional! Get the right one.
    The other problem is there isn't a barb on the port I made for the intake.. I just used a piece of 1/2-inch aluminum tubing and had it welded in. As a result, there's some shmutz around the back of the intake where it gets by the hose. Grime and whatnot. I'm going to change intakes (C3B to a C3BX, mainly due to an additional heater hose port on the C3Bx that I need), and I'll tap a bigger hole and use a screw-in brass fitting with a barb, and a spring-style hose clamp.

    -Brad
     
  16. Let us now what happens when it belches fire on a backfire and then you have a block explosion :eek:. The PCV is a oneway valve to prevent such a thing from happening.
     
  17. Roscoe7
    Joined: Jul 2, 2009
    Posts: 29

    Roscoe7
    Member

    I did this to try and keep the stock (ish) look. It works well.

    Please excuse the filth, a good clean up is coming.

    DSC00758.jpg DSC00759.jpg .
     
  18. JAWS
    Joined: Jul 22, 2005
    Posts: 1,846

    JAWS
    Member


    You mean to tell me that a backfire will travel from the open airfilter housing, down the 3/8 rubber hose past the closed pcv valve, through the valve cover into the valley then to the crankcase where it would then light off the fumes from the too rich mixture caused cylinder washed fuel/oil mix?
     
  19. JAWS
    Joined: Jul 22, 2005
    Posts: 1,846

    JAWS
    Member

    Maybe I should clarify the installation.

    PCV valve and hose connected to the bottom of the airfilter housing.
    Vent/breather in the valvecovers.

    The advantage here is that the vac caused by air intake will coincide with throttle . The more throttle the more vacuum. At the same time the pull from the vac of the fresh air through the filters in the valve covers will actually help with oil returning to the pan.

    Instead of the standard one valve cover breather and PCV in the other. Where fresh air is pulled from one side and up the other, inhibiting the oil return on the one side.

    That and there is not a constant vacuum leak at the carb. Making the tune you set be for the engine and not to compensate for a PCV.
     
  20. 26 roadster
    Joined: Apr 21, 2008
    Posts: 2,015

    26 roadster
    Member

    I have used the fuel pump block of plate with good luck.
     
  21. Got it, I read it as the hose had a clear passage from the aircleaner to crankcase.
     
  22. langy
    Joined: Apr 27, 2006
    Posts: 5,735

    langy
    Member Emeritus

  23. wildearp
    Joined: Oct 24, 2007
    Posts: 522

    wildearp
    Member
    from tucson, az

    Excellent. I will try that on a future project.

    Loctite: Only a drop is needed. You applied enough for several screws. ;)
     
  24. oldrelics
    Joined: Apr 7, 2008
    Posts: 1,728

    oldrelics
    Member
    from Calgary

    Finished the system and works great!
     
  25. daddio211
    Joined: Aug 26, 2008
    Posts: 5,998

    daddio211
    Member

    Details! Details! Details please!
     
  26. Commish
    Joined: Jan 9, 2010
    Posts: 379

    Commish
    Member
    from NW Ok

    Jaws, pcv valves are designed to work at full manifold vacuum and the do most of their work at idle or low cruising rpm, it is not unusual to get the fresh air supply from the air cleaner. I never heard of one designed to use venturi vacuum as a source, as you would basically only be getting any use out of it at high rpm, and then your throttle plates are wide open and you are not getting a buildup of blowby in the crankcase. You may be getting by with it, but I don't think it is really doing what it is supposed to.
     
  27. tommy
    Joined: Mar 3, 2001
    Posts: 14,758

    tommy
    Member Emeritus

    [​IMG]
    Actually PCV valves are designed to flow less at high vacuum conditions such as idling and cruising. Check out this drawing. Under a load the vacuum drops and the spring opens valve wider allowing more air flow when it is needed under a load. At idle the the vacuum forces the pintle into the opening reducing the air flow. Exactly opposite of what you would guess.

    Yes if you add a PCV valve to an engine, the idle screws will need to be adjusted for the added air that does not go through the carb. That is why factory installations are at the base of the carb so that the mixture does not lean out any particular cylinder.
    [​IMG]
    Some people get confused about a "closed system" that has the breather connected to the air cleaner. That hose is for the rare case when the PCV system can't keep up with the blow by. Instead of backing up and coming out on the engine the overflow of gasses gets sucked down the intake but that is not the source of the vacuum. It's strictly an overflow for blow by gasses on long grades and other long heavy load occasions. The white element in the side of the aircleaner is where the air enters the crankcase under normal circumstances. Under a heavy load the gasses can back up into the aircleaner. On a worn engine they can get very oily.
     
    Last edited: Aug 17, 2011
  28. oldrelics
    Joined: Apr 7, 2008
    Posts: 1,728

    oldrelics
    Member
    from Calgary

    I added a pic and description to the original post.....
     
  29. hammeredt
    Joined: Mar 3, 2006
    Posts: 402

    hammeredt
    Member
    from Austin,TX

    A part Number on the "newer Nissan" valve would be helpful. Do you recall what it is?

    Thanks.
     

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