Vacuum Question

Discussion in 'Engine & Performance' started by marks86, Feb 2, 2011.

  1. marks86

    marks86 Full Access Member

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    I have an 86 k10 with a 4.3 with a shit ton of vacuum lines, I was woundering if I could just buy a aftermarket chrome air cleaner housing, the stock one has a few lines going to it, so if I bought an aftermaket one what would I do with those lines just plug them up? Also one of those lines is the PCB line which runs from the drivers side valve cover to the air cleaner house to this little beather inside the air cleaner housing itself, I was woundering if I could remove that line and put a screw on oil filter on the valve cover

    I drove around with a vacuum line disconnected and my truck ran like crap, im just nervous this will happen when I remove these ones
     
  2. 89Suburban

    89Suburban Full Access Member

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    Welcome to the site man. Got a pic of it? Depends what the vacuum lines are for and how strict the emmisions test are for your area. There might be one hose for the trap door on the intake snorkel. And one should be a larger breather hose coming from the valve cover. If ya got a camera, take a pic of the hose diagram under the hood next to the radiator and post it up here for inspection. :popcorn:
     
  3. marks86

    marks86 Full Access Member

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    alright, well what if i got a new carb which i will be soon, what do I do with the old lines the dont connect to the new carb.
     
  4. 89Suburban

    89Suburban Full Access Member

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    DDamn, where is HRPC when ya need him. I don;t know, I would have to see what exactly ya have going on there. So are you saying that your are buying an aftermarket carb for it? I didn't know they made them for V-6's. :think:
     
  5. skysurfer

    skysurfer Full Access Member

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    You have vaccuum lines going to your air cleaner?


    With regards to the pcv line, I eliminated the breather tube that ran from the valve cover to the tbi choke collar when I did the tbi salad bowl mod. I put a breather in the valve cover instead. At high rpm's I was building crankcase pressure and it started blowing oil out of the dipstick tube. After tossing the breather I modified the bowl to include a vent tube and all was good. Your results may vary.
     
  6. marks86

    marks86 Full Access Member

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    A holly 600 would work fine, so if i get rid of a line should a just put a cap or a screw on it
     
  7. 89Suburban

    89Suburban Full Access Member

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    You can, but emmisions inspectiion mechanics don;t like to see that chit. And it depends on what the hose is for. I think I got my book in my truck, let me see if it shows it for your truck....
     
  8. 89Suburban

    89Suburban Full Access Member

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    I looked in the book, but there isn;t anything much in there. Just make sure you have your PCV valve hose going to the base of the carb. You can get rid of the EGR hose. And watch your breather hose. Some chrome air cleaner kits come with a base that has a port built into it fo that hose. And if ya got a hose running to your distributor you need that hooked up too. What else....hmmm... I think the rest is just emmisions crap. OH, and one might be a MAP hose, and if it is you definately need that. Like I said, we need to see what ya got there to help ya out.
     
  9. marks86

    marks86 Full Access Member

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    Thank you for the help, I got a ton more questions cuz as you can see im a newb at this stuff, Ill put of a build thread one of these days feel free to check it out
     
  10. 89Suburban

    89Suburban Full Access Member

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    No problem brother, these guys here know thier stuff. Don;t be afraid to post and ask questions. That's what were here for. :High 5:
     
  11. bucket

    bucket Super Moderator Staff Member

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    A K10 with a 4.3? Is it original? I know a C10 was standard with the 4.3, but I didn't think you could get one in a 4x4.
     
  12. RetroC10Sport

    RetroC10Sport Super Moderator Staff Member

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    Yes they did. I worked on a farm one summer and they had one. :waytogo:
     
  13. bucket

    bucket Super Moderator Staff Member

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    Hmm, that's cool. And rare too I guess. I saw one in a K5 once, but It was swapped in according to the owner. But he also didn't say what was in there before.
     
  14. Old77

    Old77 Super Moderator Staff Member

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    Wow...until now I didn't know 4.3 were available in K10's. Welcome to the site man! Post up often and show us some pics of your rig dude :handshake:
     
  15. HotRodPC

    HotRodPC Administrator Staff Member

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    I'm skipping alot of posts here, so if noone has answered yet, the only vac lines you should have to the air cleaner is for the Thermo Vac flapper which is only used during cold start up. That is what the heat riser tube off the exhaust manifold is for. So if you go with an aftermarket air cleaner, then yes, block off that vac line, and you can also remover the heat riser tube since it will not longer be functional. Another question. Does your state require emissions testings??? IF so, do they do visual inspection, tailpipe testing or both??? If they do visual, you better keep that thermostatic OEM air cleaner to put on when you go to the smog inspection station. When you do change carbs, just pay attention to what lines do what, and you should be fine. Familiarize yourself with ported vacuum, manifold vacuum and throttle plate vacuum which is manifold vacuum in my opinion. However, for emissions testing, you'll want the vac lines to the correct home or that same purpose on an aftermarket carb. You should want them in the right place anyway for proper performance. Example 1 being, vacuum advance from the dizzy goes to ported vacuum off the carb. It may not appear that way since many times the ported vacuum goes to a tvs (Thermal Vacuum Switch), which is likey in the thermostat housing or front of the intake manifold. This keeps your timing from being able to be vacuum advanced until the motor is warmed up. Alot of people say or think these vacuum lines and TVS etc is all BS and unnecessary. If those people who say that, knew what they were talking about, they'd realize the purposes make alot of sense, and they don't hurt the horsepower at all as many think and it really does reduce emissions and can also improve mpg and hp too. Also keeps your motor running better for longer between tune ups.
     
    Last edited: Feb 3, 2011

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