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Carb and vacuum line problems

Discussion in 'Engine & Performance' started by Ewhitaker0020, Apr 21, 2019.

  1. Ewhitaker0020

    Ewhitaker0020 Junior Member

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    Truck Year:
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    Engine Size:
    305 5.0
    I will be keeping the charcoal canister to let the gas have somewhere to expand to. Do I plug off the unused ports on the canister or let them vent to atmosphere? Also, I think my pcv valve just has one outlet.
     
  2. DoubleDingo

    DoubleDingo Vacuum Leaks, The Root Of All Evil

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    81-C20 Silverado Camper Special-TH400-4.10s; 65-C20 with 4:57 gears and Borg Warner Overdrive
    Engine Size:
    Carb'ed Vortec 350; 1972 L48 350
    If it were me I'd run the hoses from the canister to the proper places.
     
  3. gotyourgoat

    gotyourgoat Full Access Member

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    Ok lost light yesterday. I hope these make sense, just replaced 2 dryrotted caps for the blue ones which I believe are the egr and related ports. One would also be for power brakes(the tee I'm guessing) which I don't have.
    20190424_112700.jpg Dizzy line kinda hidden but comes out under the rusty gas line fitting.
    20190424_112544.jpg
    The can has 5 ports left to right in pic they are gas tank, for the center valve the larger bottom line for carb, on top of that is the pcv. Far right valve is another pcv connection from the splitter shown. Top hose goes down the frame and as far as I recall is the atmosphere vent.
     
    Last edited: Apr 24, 2019
  4. Ewhitaker0020

    Ewhitaker0020 Junior Member

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    Engine Size:
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    I will be. I just looked over the vacuum diagram and I'm going to run all the canister lines like it shows. I do have a question though. On the diagram it shows 2 tvs ports. I googled these and Google says theirth thermal vacuum switches. Does this mean they only open or close when my truck is at a certain temperature? And I saw 1 vacuum 'tree' on my water neck and one right next to it on the intake manifold. Are these the tvs's? If I'm going to have some unused ports (such as the egr valve) do I just block these ports off? One of these ports goes to my egr and egr bleed solenoid then after the solenoid it goes to the rear port of my carb. Since I won't have the egr and by relation the egr bleed solenoid would I just take that port straight to the back of my carb?

    I guess a big question is do I even need my egr valve? I was planning on just blocking off the plate if I don't need it.

    IMG_20190421_102910.jpg
     
  5. Ewhitaker0020

    Ewhitaker0020 Junior Member

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    I guess my canister and carb are a little different than yours. My canister has 4 separate ports on the top of it, with the left most going to the air cleaner. Also on my carb my rear port is for the egr which I plan on deleting.

    I don't see one on my canister that vents to the atmosphere. It might be the one that goes to my air cleaner since that probably burns the gas fumes from the canister.

    IMG_20190421_102910.jpg

    IMG_20190421_102925.jpg
     
  6. DoubleDingo

    DoubleDingo Vacuum Leaks, The Root Of All Evil

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    Truck Year:
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    Truck Model:
    81-C20 Silverado Camper Special-TH400-4.10s; 65-C20 with 4:57 gears and Borg Warner Overdrive
    Engine Size:
    Carb'ed Vortec 350; 1972 L48 350
    I've asked similar questions about what those things are but never got an answer. I think you are correct on how it works, though. Your canister doesn't seem to match the sticker, or the air cleaner is different. My canister looks like the clean one @gotyourgoat posted up.
     
  7. Ewhitaker0020

    Ewhitaker0020 Junior Member

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    My canister looks just like my sticker. 4 separate ports with the 2 on the right having an extra port on top of each.
     
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  8. gotyourgoat

    gotyourgoat Full Access Member

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    For reference this is the original unit I replaced a couple weeks ago. There is usually some variety of little vent/airlock thing (which does not have a hose connected to it) next to the gas tank port. Where the hole is on the right in this pic 20190424_140323.jpg
     
  9. Ewhitaker0020

    Ewhitaker0020 Junior Member

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    I don't see one on mine. Maybe on mine it's the one that goes to the air cleaner. Where you have a hole I have another port and the vacuum diagram says it goes to the air cleaner.
     
  10. DoubleDingo

    DoubleDingo Vacuum Leaks, The Root Of All Evil

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    Truck Year:
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    Truck Model:
    81-C20 Silverado Camper Special-TH400-4.10s; 65-C20 with 4:57 gears and Borg Warner Overdrive
    Engine Size:
    Carb'ed Vortec 350; 1972 L48 350
    I had to go back and look again. With all the dirt on top the bottom ports look to be non-existent.
     
  11. Ewhitaker0020

    Ewhitaker0020 Junior Member

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    What are you trying to say?? Do you think my canister is dirty? I've got a lot of work to do to this truck before I get it back on the road again. What's this transmission cable I keep hearing about people adjusting.
     
  12. DoubleDingo

    DoubleDingo Vacuum Leaks, The Root Of All Evil

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    Truck Year:
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    Truck Model:
    81-C20 Silverado Camper Special-TH400-4.10s; 65-C20 with 4:57 gears and Borg Warner Overdrive
    Engine Size:
    Carb'ed Vortec 350; 1972 L48 350
    You're on the right track, and all that you're doing will make it run way better than it was. I don't have a trans cable so I'll let others answer that one.
     
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  13. gotyourgoat

    gotyourgoat Full Access Member

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    My sticker has so much over spray on it the thing is pretty useless. The line on the can I labeled vent is incorrect. My previous owner removed the egr. It is the purge signal hose (which goes to the egr) in your label. Not sure where I'd even hook that line up to at this point.
     
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  14. DoubleDingo

    DoubleDingo Vacuum Leaks, The Root Of All Evil

    Posts:
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    Joined:
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    Shane
    Truck Year:
    1981, 1965
    Truck Model:
    81-C20 Silverado Camper Special-TH400-4.10s; 65-C20 with 4:57 gears and Borg Warner Overdrive
    Engine Size:
    Carb'ed Vortec 350; 1972 L48 350
    This is a setup with no EGR, no CAT(s), just the A.I.R. stuff, and there is no lack of power whatsoever with the A.I.R. stuff hooked up. I know your A.I.R. stuff is coming off, just letting you know it doesn't rob any power from the engine.

    2012-08-05_17-10-17_567.jpg
     
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  15. Ewhitaker0020

    Ewhitaker0020 Junior Member

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    Engine Size:
    305 5.0

    Honestly, it's really just an asthetics thing at this point the tubes off of the exhaust manifold are obtrusive and ugly. I'm thinking about installing some plugs into the holes if I can even remove the tubes, they're pretty rusty. If they give me trouble I'll just leave them on there.
     

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