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PCV Revised - No holes in Manifold or Valve Covers

Discussion in 'The Hokey Ass Message Board' started by Roadsterpu, Sep 2, 2012.

  1. Roadsterpu
    Joined: Nov 10, 2008
    Posts: 895

    Roadsterpu
    Member

    I was facing a very similar issue that most people on the HAMB faces, how do you add a PCV to a motor when you do not want to drill your valve covers or your manifold. I have read many threads on the subject and most suggested drilling a hole in the back of the manifold for a threaded PCV valve. I also knew that the original road draft tubes pulled from the back of the block in the lifter valley. I have a late 60's NOS Fenton 3 deuce manifold and after searching for a few years finally found a set of original Fenton valve covers. Needless to say I did not want to drill either. SO what to do now? I asked a fellow HAMBer, Crazydaddyo, for some ideas. He had a great one, run a line from the carb through the oil fill tube under the manifold to the back of the block near the distributor.

    Here is how I did it.

    Here are the parts I used. 5/16" copper line, tube nut, 1/8 NPT to 5/16" tube 90' adapter, 3/8 hose barb and length of clear tube.
    [​IMG]

    The PCV is from a 64 Chevy small block with 2 barrel (Napa part # CRB 29255). It threads into the carb base. I used a 90' elbow to get the room I needed.
    [​IMG]

    I first flattened an area on the oil fill tube for the adapter and hose barb to mate up against. I had to cut some of the NPT side of the adapter off to get it to fit inside the oil fill tube. I also flared the copper tubing and attached it to the adapter.
    [​IMG]

    Bent the tubing to fit the manifold and put a couple of coils into it to act as a baffle. Bent the tubing to follow the underside of the manifold. I drilled and tapped a bolt boss to accept an 8-32 screw so I would clamp the tube to the manifold. I did not want the tubing to crack from vibration.
    [​IMG]

    I drilled a small hole in the bottom of the coils to act as a drain for any oil that may find its way inside.
    [​IMG]

    I used clear tubing to kind of hide it on the manifold. I thought that maybe the clear tubing might not be so obvious. If it clouds up in time I will replace it with black line.
    [​IMG]

    If I find that I am still sucking oil into the PCV, I am going to add a oil separator. I plan on using a reusable fuel filter housing filled with fine steel wool. This should filter the oil out of the air pretty well.

    I hope this helps others who might be in the same predicament.
     
  2. upspirate
    Joined: Apr 15, 2012
    Posts: 2,281

    upspirate
    Member

    Nice.
    I was just going to drill the manifold behind the rear carb for a pcv valve grommet then hose to the carb base.

    I liked the other mystery one on here too that had copper tube plumbed to the plenum on underside of a flathead intake with an inline pcv attached to the copper tube....all hidden under the intake,but not accessible for maintenance w/o pulling the manifold.

    Thanks for the tech photos....let us know how well it works and any drawbacks
     
  3. I would add a few more oil drain holes, can't hurt. Great idea!
     
  4. Roadsterpu
    Joined: Nov 10, 2008
    Posts: 895

    Roadsterpu
    Member

    I was thinking those might not be enough to get the oil to drain though. I was kind of relying on the people here to tell if I needed more. I was right you guys did tell me. :D:D:D:D
     

  5. seb fontana
    Joined: Sep 1, 2005
    Posts: 7,071

    seb fontana
    Member
    from ct

    "''64 Chevy small block with 2 barrel (Napa part # CRB 29255''"

    Where did this go in the original application? I sorta feel its in backwards...
     
  6. VoodooTwin
    Joined: Jul 13, 2011
    Posts: 3,455

    VoodooTwin
    Member
    from Noo Yawk

    If thats a vented breather, the path of least resistance (air flow-wise) is through the oil fill breather. Not sure how effective that system will be. But it's a cool solution.
     
  7. M_S
    Joined: Feb 20, 2008
    Posts: 542

    M_S
    Member
    from SoCal

    The oil fill tube.
     
  8. seb fontana
    Joined: Sep 1, 2005
    Posts: 7,071

    seb fontana
    Member
    from ct

    It screwed into the oil fill tube so it is in backwards..Put the valve at the fill tube [screw in] and the hose end at the carb and run the hose.. This puts the air path/operation right...May or may not cure oil problem...An oil separator will work but I have found that once they accumulate an amount of oil [doesn't take very long] they will pass any more that goes in..
     
  9. It's a creative idea but I'm not sure that it will work very well. If you look at a diagram of a PCV system you will see that you need a breather at another point on the system. if the PCV is in the front the breather should be in the back. If the PCV is on one valve cover then the should be on the opposite valve cover. With the design you have, you essentially have the PCV and the vent in the same location (the fill tube). This will not allow the valve to work effectively. It will probably just pull in fresh air through the vent.

    On the '67 Chevy that used a PCV in the fill tube, the fill tube was not vented. The vent hole in the back of the block (pre-1968 blocks) went to the air cleaner, I think. Those of us who drill a hole in the manifold for the PCV usually run a vented fill tube up front. With the vented fill tube and the PCV at the back of the manifold it is a functional system. I don't think yours is going to work.

    I hope that made sense.

    Also, as mentioned above. If you are running the PCV at the carb base and the valve was originally intended for a fill tube application then the valve is flowing the wrong direction. You'll have to use a different one. I think the one I used was a Fram FV-100? I'm not positive about that though.
     
  10. seb fontana
    Joined: Sep 1, 2005
    Posts: 7,071

    seb fontana
    Member
    from ct

    Saxman, did you look at the pics? Thats what the copper tube is for; to get air from back of valley while fresh air comes in from oil fill/breather..
     
  11. VoodooTwin
    Joined: Jul 13, 2011
    Posts: 3,455

    VoodooTwin
    Member
    from Noo Yawk

    Is the copper tubing hard-connected to the nipple on the vent tube? If so, then the system is complete and in theory should work. The small diameter copper tube may be too small to handle the airflow, but I hope it works. That's a tidy system.
     
  12. Obviously not.
    But there's still some great info in the post.


    A baffle constructed similar to the original used on the early blocks attached to the copper tube would work much better. I've seen (read on the internet) where a lawn mover muffler has been used for a valley baffle. I think a larger copper tube would be beneficial to the system.

    The coils aren't really any type of baffle, its more like a silly straw. The drain holes and the coils really aren't doing anything close to what they are there for. - baffle and oil drain.

    This is a very cool idea that needs a real honest baffle. Something with an air break attached to the end of the tube

    Oh yeah, safety wire on that little screw.
     

  13. In the original application of this specific PCV valve, it screwed in the carb base just like the OP has it.
     
  14. hanginlow58
    Joined: Sep 16, 2003
    Posts: 364

    hanginlow58
    Member

    pretty sure thats going to suck up oil like mine did after you get up to freeway speed for 20 minutes or so, im experimenting with this problem right now, i drilled the back of my manifold and had the pcv coming out with a baffled grommet right where yours is at , i was all happy with it till i got the rpm's wound up for a while, good luck with that i will be waiting to hear if that does work.
     
  15. fordor41
    Joined: Jul 2, 2008
    Posts: 958

    fordor41
    Member

    I'd say the PCV will pull more air than the copper tube can replace and you will suck oil from the crankcase. I think you're on the right path if you can at least match or exceed incoming air flow to the PCV air flow.
     
  16. tommy
    Joined: Mar 3, 2001
    Posts: 14,757

    tommy
    Member Emeritus

    My only worry is that there will not be enough baffling to prevent oil from being sucked up.

    [​IMG]

    This is the valley breather baffle for road draft and early PCV systems. I don't see anything like it in your system. You can make your own with a homemade can filled with a copper pot scrubber from any super market.

    [​IMG]

    I have used Scotch-brite from the supermarket for the old hot rod style breathers. cut it in strips and insert into the breather.

    There needs to be some kind of baffle to prevent excess oil consumption. JMHO.
     
  17. davidbistolas
    Joined: May 21, 2010
    Posts: 962

    davidbistolas
    Member

    Damn, I wish I thought of that copper tubing pvc line in the lifter valley trick.
     
  18. big creep
    Joined: Feb 5, 2008
    Posts: 2,945

    big creep
    Member

    roadsterpu where did you get your progressive link for your tri power?
     
  19. Roadsterpu
    Joined: Nov 10, 2008
    Posts: 895

    Roadsterpu
    Member

    The airflow on PCV i have goes from the hose barb to the threaded end. This PCV is intended to be screwed in the carb base so the direction is correct.

    The copper line is hard connected to the hose barb through 90' elbow. It is flared so there are no leaks at that connection. I used thread tape on the hose barb at the oil fill tube so again no leaks there. The hose barb and 90' elbow surface mount to the fill tube so that should eliminate leaks there. Since the line from the carb to the oil fill tube to the copper line is sealed up, theoretically the PCV is pulling air from the back of the block in the lifter valley. This is as close as I could get to the original PCV systems Chevy used.

    I think I want a separator outside as I would like it serviceable. I may add a separator inline between the oil fill tube and the PCV. I already have an idea of one. I plan on using a reusable fuel filter housing filled with fine steel wool. This should filter the oil out of the air pretty well. Would the separator be OK outside of the valley?

    What ideas of ensuring the screw does come out on me? I was thinking of using red locktight.

    So is the consensus that the 5/16" line is too small? The problem I have with going bigger is the tight confines of the oil fill tube. The adapter needs to fit in there.


    Big Creep: My linkage came from Vintage Speed in FL.
    http://www.vintagespeed.com/
     
  20. Roadsterpu
    Joined: Nov 10, 2008
    Posts: 895

    Roadsterpu
    Member

    Would a valley baffle work to keep the oil out of the tube? The type of baffle I am talking about is used to keep oil off the underside of the manifold to keep in the intake charge cooler.

    Something like this.
    http://www.summitracing.com/parts/MOR-25050/?rtype=10
    [​IMG]
     
  21. dickster27
    Joined: Feb 28, 2004
    Posts: 3,199

    dickster27
    Member
    from Texas

    Even if this idea will work, it is for 2G's only as the 94's and 97's have no base opening for the valve. I still think the cleanest setup is to drill and tap a 1/8" NPT in the rear of the intake just forward of the dizzy and screw in a Napa # 2-9337 in and attach a 5/16" length of hose to a nipple that you have placed in either a ready made 1/8" NPT hole in the intake or a drilled and taped hole in vacuum chamber under one of the carbies. I epoxy an aluminum shroud under the PCV opening under the intake. Oh, this is a great smaller sized PCV valve that was originally used on GM V8 trucks. Don't mean to kill your post but this idea has been tried and proven many times over and can be used with whatever carbie setup you have.
     
  22. upspirate
    Joined: Apr 15, 2012
    Posts: 2,281

    upspirate
    Member

    Hangin,did you ever get this sorted out? I was going the same route once I found the baffled grommet,but may have to figure out some other baffle too....maybe that valley tray baffle that was posted?
    Damn Corvette valve covers!!
     
  23. tommy
    Joined: Mar 3, 2001
    Posts: 14,757

    tommy
    Member Emeritus

    you can't tell simply by the threaded end.

    [​IMG]

    this is like the one seen above that screws into the carb base on Rochester's.

    Chevrolet also made a threaded PCV valve that screws into the oil filler tube on Corvettes but the flow is opposite of this one. I always blow through the valve to make sure of the direction of the flow.
     
  24. R Pope
    Joined: Jan 23, 2006
    Posts: 3,309

    R Pope
    Member

    The older SBC's had an air dam rivetted to the intake to force the moving air down through the crankcase. Your setup will just vent the valley and not suck any moisture out of the pan area. I would build a piece of sheet metal to block most of the valley.
     
  25. Roadsterpu
    Joined: Nov 10, 2008
    Posts: 895

    Roadsterpu
    Member

    Dickster: You are right, however, your solution doesn't help me because I do not want to drill a hole into my manifold. My solution here essentially puts the air intake in the same location. Is there something in my set up hat is different in function to what you have suggested?

    Tommy: I blew through the valve to ensure it had the correct flow direction.

    R Pope: Do you mean to divert the air from the oil fill tube breather? prevent the PCV from just taking air from the top of the valley?

    Dickster:
    How does your solution address what R Pope is referring to?
     
  26. dickster27
    Joined: Feb 28, 2004
    Posts: 3,199

    dickster27
    Member
    from Texas

    Well, the aluminum baffle I suggested will divert the oil. As far as R pope's theory is concerned, that kinda blows the idea of the millions of SBC's out there with aftermarket intakes drawing through the head, which is more restrictive than the valley. So, his principle means they don't work. The sheet metal baffle on the bottom of factory intakes is the keep the exhaust crossover under the middle carbie from frying the oil.
     
  27. hanginlow58
    Joined: Sep 16, 2003
    Posts: 364

    hanginlow58
    Member

    not yet! im waiting on parts now to try the pcv in the oil fill tube and vent it through the hole i drilled, i seen that valley tray and will try that if this does not work, there is just too much oil splashing around in there at high rpm's but damn im determined to use my new chrome valve covers
     
  28. von Dyck
    Joined: Apr 12, 2007
    Posts: 678

    von Dyck
    Member

    Hanginlow, I experienced the same phenomenon as you - sucked a fair bit of oil at highway RPM. (didn't want to cross flow my vintage Edelbrock covers) I built my own oil vapor separator patterned after the original GM design and mounted it under the Vette aluminum intake just ahead of the distributor and a fully vented oil beather cap. I reluctantly removed the Edelbrocks and went with the factory stamped cross flow PCV covers. No more oil consumption.
    It'll be interesting to see how this one works out.
    The proof is still in the pudding!
     
  29. PackardWood
    Joined: Aug 13, 2012
    Posts: 485

    PackardWood
    Member
    from JoCo, NC

    I would bypass the steel wool filter to keep the pulse to the carb as strong as possible. As for the tubing size, if the smallest diameter on the PCV is bigger then the copper tube then yes you need to go bigger, they make the same 90 degree fittings in a bigger size. I would add another two loops to the coil, drill 2-3 holes in the bottom of each about twice the size of the ones you have and the oil should drain back fine. Pretty slick engineering you have there! The only part of the whole deal I don't like is the clear tubing, it is great for now as you can see if it is still sucking up oil. After you get the oil thing sorted out I would look for a large diameter chrome fuel rail or make what you need out of copper of brass and have that one part chromed. Looks like a sweet ride so it is for sure worth the P I T A of doing it all 110%.
     
  30. Roadsterpu
    Joined: Nov 10, 2008
    Posts: 895

    Roadsterpu
    Member

    Thanks guys for the input. I really appreciate the help. Looks like I have some thinking to do. Need to see what is available for the tubing in a bigger size while still being able to fit everything in there.
     

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