Register now to get rid of these ads!

Hot Rods pcv or draft tube??

Discussion in 'The Hokey Ass Message Board' started by buick bill, Sep 6, 2019.

  1. buick bill
    Joined: Dec 18, 2008
    Posts: 240

    buick bill
    Member
    from yreka;ca

    what is the best way to go .draft tube or pcv . my mtr is 235 chev, I don't think any originaly had pvc , but I think ca made them retrofit some early cars . should it matter to the motor .one way or the other . I like the clean look of a draft tube .
     
    Last edited: Sep 6, 2019
  2. Fordors
    Joined: Sep 22, 2016
    Posts: 2,064

    Fordors
    Member

    Without knowing what shape your car is in, if you had ever breathed the fumes coming from a draft tube at a traffic light you would opt for the PCV system. Even if your engine has no blow by fumes the PCV is superior in every way.
     
    Deuces, lothiandon1940 and nunattax like this.
  3. buick bill
    Joined: Dec 18, 2008
    Posts: 240

    buick bill
    Member
    from yreka;ca

    we all know what I meant , but what I wrote isn't at all what it was !!
     
    Register now to get rid of these ads!

  4. scrap metal 48
    Joined: Sep 6, 2009
    Posts: 5,620

    scrap metal 48
    Member

    PCV.. Why pollute???
     
    G-son, Deuces and lothiandon1940 like this.
  5. Dyno Dave
    Joined: Feb 18, 2011
    Posts: 220

    Dyno Dave
    Member

    Have a '54 Bel Air 2dr. sedan, replaced the vacuum wiper motor with an electric 12v unit from a '57 Chev. This left the 2 intake vacuum ports open, did a 2 hole tubing manifold and and hid the PVC behind the valve cover...
    The '57 2 speed wiper was a direct bolt. dyno dave
     
    scrap metal 48 likes this.
  6. VANDENPLAS
    Joined: Dec 14, 2009
    Posts: 1,840

    VANDENPLAS
    Member

    I used a 261 out of a 59 Chevy with factory pcv in my fleetline
    Perfect fit and solution
     
  7. nunattax
    Joined: Jan 10, 2011
    Posts: 1,850

    nunattax
    Member

    allways had a PCV in my sbc but only connected it up lately.using a 90 degree thru firewall fitting at the filter base.havnt smelt any fumes since.
     
    Last edited: Sep 6, 2019
  8. Blue One
    Joined: Feb 6, 2010
    Posts: 9,723

    Blue One
    ALLIANCE MEMBER
    from Alberta

    PVC is for plumbing.
     
  9. AngleDrive
    Joined: Mar 9, 2006
    Posts: 673

    AngleDrive
    ALLIANCE MEMBER
    from Florida

    But you could use it for a draft tube
     
    cactus1 and scrap metal 48 like this.
  10. Truckdoctor Andy
    Joined: Jan 13, 2017
    Posts: 794

    Truckdoctor Andy
    Member

  11. Moriarity
    Joined: Apr 11, 2001
    Posts: 14,976

    Moriarity
    SUPER MODERATOR
    Staff Member

    I fixed the title. positive crankcase ventilation .... not poly vinyl chloride....
     
  12. KoolKat-57
    Joined: Feb 22, 2010
    Posts: 2,808

    KoolKat-57
    Member
    from Dublin, OH

    PCV, on all my cars.
    Road draft tubes stink!
    KK
     
    Deuces likes this.
  13. a boner
    Joined: Dec 25, 2004
    Posts: 5,116

    a boner
    Member

    PCV.....actually a good (rare) government mandated upgrade.
     
    Last edited: Sep 6, 2019
    Deuces likes this.
  14. sunbeam
    Joined: Oct 22, 2010
    Posts: 4,211

    sunbeam
    Member

    The clean look of a road draft tube on the outside but it won't look that way inside.
     
  15. PCV also does a better job of drawing moisture out of the crankcase.
     
    Deuces likes this.
  16. saltflats
    Joined: Aug 14, 2007
    Posts: 9,424

    saltflats
    Member
    from Missouri

    It also pollutes the induction system. ;)
     
    enigma57 likes this.
  17. I agree with the PCV option, BUT, this all depends if the Carb(s) are metered for the flow from the PCV system!!! I have seen many that are connected to anywhere there is vacuum and think its ''Golden'' when its not. So what ever the carb (s) are metered for will dictate the direction you should go. JW
     
    RMR&C likes this.
  18. deathrowdave
    Joined: May 27, 2014
    Posts: 1,709

    deathrowdave
    ALLIANCE MEMBER
    from NKy

    PCV is by far light years ahead of a road draft tube . My old diesel has a slobber tube , it doesn’t stink so ad but it always drips .
     
    Truckdoctor Andy likes this.
  19. gimpyshotrods
    Joined: May 20, 2009
    Posts: 16,140

    gimpyshotrods
    Member

    Get a core plug (sometimes mistakenly called a freeze plug) that fits where the road draft tube did.

    Drill a hole in the center of it, toss a PCV valve grommet, and a straight-up PCV valve in it. Plumb it straight up, and over and attach it to the manifold.
     
    Truckdoctor Andy, Deuces and a boner like this.
  20. I switched to a pcv system on my 61 Ranch Wagon. An older gentlemen that bought a similar car new asked me about it and said, “I don’t blame you, that damn thing smoked and stunk on the way home from the dealer”
     
    Deuces and lothiandon1940 like this.
  21. jimmy six
    Joined: Mar 21, 2006
    Posts: 4,547

    jimmy six
    ALLIANCE MEMBER

    As told by engineers in 1961 PCV “ positively contaminating valves”. On my Y - Block ( yes it did stink) I put on a breather cap with a 1/2” hose fitting which I plumbed in to the air cleaner and left the crankcase breather open.... no more stink or oil dripping.
     
    Last edited: Sep 6, 2019
    enigma57 and wraymen like this.
  22. Did ya ask them why didn't they design it that way in the first place.;)
     
  23. Fordors
    Joined: Sep 22, 2016
    Posts: 2,064

    Fordors
    Member

    Actually closed crankcase systems were used years before the govt. requirement came into effect. Slow moving vehicles like a milk delivery truck or military stuff that might run in deep water did not use draft tubes.
     
    gimpyshotrods likes this.
  24. I remember reading that Willys Corp reported longer ring life in their experiments with positive crankcase ventilation in the 1950s, years before it was required by law for emissions reasons.
    I've added pcv systems myself on older engines.
    Usually successful, but a few times I accidently ended up with over-venting and increased oil consumption, but most times it worked out fine.
    I still use an old road tube system on my truck, and tell myself that one day I might experiment with adding a pcv, but I will wait until I'm ready to debug if something doesn't match the amount of venting that's apropriate. I don't want to put together a mismatch that over vents again :)

    WHY BE ORDINARY ?
     
  25. If attached to the manifold, how do do overcome the air leak you have now created.... only if the carb is metered for the PCV system will this work, then why not just connect to the carb fitting that is for this function. JW
     
    enigma57 likes this.
  26. gimpyshotrods
    Joined: May 20, 2009
    Posts: 16,140

    gimpyshotrods
    Member

    What Chevy 235, that now has a road draft tube, also has a fitting on the carburetor for a PCV valve hose?

    You don't overcome the tiny, metered additional air flow. If it proves to be an issue, you re-jet.

    I have done 6-7 of these setups, on 216s and 235s. I have yet to detect an issue.

    I didn't come up with this, or prove that it works.

    Go see for yourself: https://www.google.com/search?q=235...54KHZ0JDKkQ_AUIEygC&biw=1536&bih=722&dpr=1.25
     
    Truckdoctor Andy likes this.
  27. Fordors
    Joined: Sep 22, 2016
    Posts: 2,064

    Fordors
    Member

    I would think that any fitting on a carburetor for PCV would not be metered, the valve is just connected to the throttle plate and sees manifold vacuum, the same as putting the PCV valve in the manifold. I never liked the idea of plugging the valve into an individual port as that feeds all vapors to one port all the time, but if tapped in right below the carb it should be fine.
    An air leak? With manifold vacuum the engine is sucking fumes, with decreased vacuum the valve closes.
     
  28. gimpyshotrods
    Joined: May 20, 2009
    Posts: 16,140

    gimpyshotrods
    Member

    Yup, and go figure, this is where you tap a 235 manifold for the hose connection:
    [​IMG]
    Right under the carburetor, servicing all ports.
     
    Truckdoctor Andy and Frankie47 like this.
  29. I stand by what i wrote, and yes, what 235 carb ( is this an original carb or newer replacement ?)on an engine with a draft tube has provision for the extra air flow under the throttle butterfly. On a carb that is metered, and yes they are metered for this extra air flow, they are very different from each other. So you have done some with no issues, good for you, no really..... sounds as good as the thread on the PCV on a Y Block that was plumbed into a back intake runner and all that said that's what i did and i it works great....BS!! JW
     
    enigma57 likes this.

Share This Page

Register now to get rid of these ads!

Archive

Copyright © 1995-2020 The Jalopy Journal: Steal our stuff, we'll kick your teeth in. Terms of Service. Privacy Policy.

Atomic Industry
Forum software by XenForo™ ©2010-2014 XenForo Ltd.