Need a port for PCV.

Discussion in 'Fuel and Air Systems' started by trevorcrum, Jan 14, 2016.

  1. trevorcrum

    trevorcrum Well-Known Member

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    All, Looking for some advice.

    I bought my 360 duster last year and although the previous owner had a PCV installed in the valve cover driver side, and a breather on the passenger, neither were hooked up to anything.


    I installed a breather tube to my air filter intake, but when trying to find a spare port for my PCV, I came up empty. My carb is a 2 corner holley double pumper 600, and only has two ports. Right now I am using one for my brake booster, and one for my vacuum advance.

    The intake is a M1, and he had a thick spacer under the carb ~ 1" thick. I'm thinking I could replace that spacer with one that had a port and plug the PCV into it, but wanted to ask if this makes sense first.

    As you can probably guess, I'm new to the hobby and don't want to cause any issues down the road.

    Thanks, Trevor.

    74 Duster 360
    0.030" over
    Lunati Voodoo cam
    M1 intake
    600 Holley DP
    Direct Connection headers
    727, 8.75 with 3.75:1 gears
     
  2. 67Dart273

    67Dart273 Well-Known Member

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    The intake doesn't have a port in the rear on the throttle side?

    You are using a 3/8 hose port on the carb for a booster? Just put a tee in there
     
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    • RustyRatRod

      RustyRatRod Just another dumbass. Technical Editor

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      The brake booster should be routed to the intake manifold. The carburetor is for the PCV valve.
       
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      • 67Dart273

        67Dart273 Well-Known Member

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        Yup. In this photo "stolen" form here, draw a mental line from the right hand secondary bore to the far top right manifold bolt hole. "That hole" in between is 3/8 pipe thread, going into the intake vacuum / port runner

        [​IMG]
         
      • 67Dart273

        67Dart273 Well-Known Member

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        Better photo. Brake booster hose coming off near right rear corner of carb, right in front of the distributor. On a TQ, the PCV comes off the front of the carb

        100_0141-jpg.jpg
         
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        • trevorcrum

          trevorcrum Well-Known Member

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          It's an M1 intake manifold, so no vacuum ports. that's why I guess the previous owner ran the brake booster to the back of the Holley DP where the PCV typically goes in. Can I just tee that thing ? or will that cause my brakes to potentially fail ?

          Or what about the spacer with a port ?

          Thanks.
           
        • trevorcrum

          trevorcrum Well-Known Member

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          m1 intake stock photo.
           

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        • RustyRatRod

          RustyRatRod Just another dumbass. Technical Editor

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          Yes, you can put a tee in at the carburetor and it will be fine.

          The reason you do not run the PCV into the intake is because you can pick up a running issue. The cylinder whose runner the PCV is on may skip or run badly, because all the PCV is, is a controlled vacuum leak.

          Running the PCV to the carburetor removes that chance, as you are pulling manifold vacuum from the entire plenum, rather than from one or two cylinders.

          The power brakes can run from te intake manifold, because once the diaphragm sees vacuum, the work is done. There is no "constant leak" like there is from a PCV valve. In effect, the brake booster becomes a vacuum canister of sorts, since there is no inlet for atmospheric pressure.

          This is why a ruptured brake booster diaphragm will make the engine run rough, because then it is a vacuum leak.
           
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          • 67Dart273

            67Dart273 Well-Known Member

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            You sure there isn't a tapping horizontally into the rear of the plenum?

            EDIT guess not. Nice of them not to provide "anything"
             
          • trevorcrum

            trevorcrum Well-Known Member

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            Thanks all. I'll run the T to the back of the carb with the Brake booster and PCV. That seems to make the most sense.
             
          • 7milesout

            7milesout Well-Known Member

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            Sorry to dredge up an old thread. But to a newbie like me, believe it or not, this short thread held a wealth of knowledge. I'm about to spend money on a drop base air cleaner. But before I do, it seems the drop base filters I'm looking at have no vacuum port like the air filter housing I have on it now.

            Currently I have the driver's side valve cover PVC hose running to the bottom front of the carb (from memory), like shown in one of the pictures above. The passenger side vacuum is ran to the vacuum port on the air filter.

            Since it looks like I may lose the vacuum port on the air filter when going to a drop base, should I tee the passenger side PVC line into the line from the driver's side valve cover, into the bottom of the carb?


            7milesout
             
          • hangn0ut

            hangn0ut Well-Known Member

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            Late answer to a late question but hey he is a newbie. Answer is NO. That line to the air cleaner is so the pvc system gets clean air. You can pick up a breather with a built in filter element. The most obvious one would be a k and n breather but many breathers can perform the same function. And look stock.
             
          • 7milesout

            7milesout Well-Known Member

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            Dumb question: What is the filter thing called that is mounted to the air cleaner base that also doubles as the connector to the breather (hose)? The purpose is to a) filter air to/from the breather, and b) provide a fitting for the breather hose.

            I'm going to get a new one when I buy a drop base filter. The current one looks like crapola.

            Thanks.
             
          • hangn0ut

            hangn0ut Well-Known Member

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            Dumb question? I don't think so,it's called a filter thingy I guess! LOL.
             
          • AJ/FormS

            AJ/FormS 367 FormS clone 3.09-1.92-1.40-1.09-.78od 3.55s

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            Those are a Chebby deal. I don't recall seeing them on a Mopar
             
          • 7milesout

            7milesout Well-Known Member

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            Then I must have a Chebby air filter base because I have an old crusty filter thingy there. :D

            I didn't know what it was for the longest time. And then when I realized it was a filter it occurred to me that it probably doesn't breath well … because it's crusty. I think it's called a breather filter. I'm not sure the value because up inside the air filter housing, that area is already filtered.
             
          • 69_340_GTS

            69_340_GTS Well-Known Member

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            Not needed, it's a GM thing. You can draw clean air from inside the air cleaner or directly from a breather on the valve cover. This breather should be something like a K&N ideally.
            knn-62-1600rd_gq_ml.jpg

            So where this diagram shows a "closed oil filler cap" with the hose to the air filter, you just eliminate the cap & hose, and put a filtered breather like this in the valve cover.
            1326301990.jpg
             
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            • 7milesout

              7milesout Well-Known Member

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              Chawesome! (That's beyond awesome). That's going to simplify the change over to the drop base filter. And ensure its actually breathing well, instead of through the ole crusty thingy in the air filter base.

              Much appreciated!
               
            • Murray

              Murray FABO Gold Member FABO Gold Member

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              History lesson (yes I am old). In the beginning there was the road draft tube to vent the crankcase ( atmospheric pressure at work). Then in the '40s came the PCV (Positive Crankcase Ventilation) using vacuum to vacate vapors and pressure in the crankcase. In this case the engine is still vented to the atmosphere. but we are pulling a vacuum on it. Then came the '60s (I love the '60s) we were concerned that these crankcase vapors would escape into the atmosphere when the engine was at rest (no vacuum). So we got the "closed system". Now we draw fresh air though the air cleaner. A PVC valve is a good idea, but where you draw your fresh air for is up to you. You can put a vented breather on the valve cover, creating an "open" system, or you can route that breather tube to the air cleaner.
               
            • AJ/FormS

              AJ/FormS 367 FormS clone 3.09-1.92-1.40-1.09-.78od 3.55s

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              Most engines at WOT, will eventually make some pressure in the CC that the PCV cannot handle. In the closed system these excess vapors go into the air filter house. In the open system they go out the VC breather and mess your engine. If your cowl seal is not working right, maybe you will be breathing them,lol.
               
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              • 65Val

                65Val Average Length Member

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                Personally, I'd drill and tap the rear of the plenum and install a 3/8" nipple to attach the power brake hose to....use the carb fitting for PCV.

                Easy, peasy.....


                Untitled.jpg
                 
                Last edited: Sep 23, 2018 at 1:46 AM
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                • hangn0ut

                  hangn0ut Well-Known Member

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                  Remember when the middle of the traffic lanes were a black streak? And motorcyclists never rode in the middle of a lane. And the first rain after summer was a time to be more careful as things got a little more slippery. LOL.
                   
                • hangn0ut

                  hangn0ut Well-Known Member

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                  PCV , PVC. What's the difference? LOL. Yeah I know....
                   
                • Murray

                  Murray FABO Gold Member FABO Gold Member

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                  OK-I'll bite. PCV= Positive Crankcase Ventilation, PVC= Polyvinylchloride. Don't you love abbreviations!
                   
                • 7milesout

                  7milesout Well-Known Member

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                  Ain't got me no power brakes, I ain't that fancy...