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Flap inside air cleaner above pre-heater: Can I yank it?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by blackdog, Aug 17, 2001.

  1. blackdog

    blackdog Registered Member

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    <font color=black>Well I know I can, but should I?

    I'm working on getting more air into the engine. The K&amp;N filter rocks, but I'm planning to covert the air cleaner to dual intake hoses like I've read on some older threads. This should be pretty easy. I thought about open element, but the hot air factor worries me.

    As far as the flap, though, it's the one just inside the air cleaner arm right above the pre-heater hose inlet. I don't really see how even the strongest or hottest blast of air could move that thing efficiently since the spring is so strong. Essentially, I think it's restricting much of the air flow.

    Any objections to ripping it out? I can't really think of too many advantages to keeping it there, except warming up in winter, and I could always rig up a way to accomplish this with more air flow. Sound good?

    <font color=black> "Where did all these people come from, and how soon can they leave..."
    -OLD 97's</font color=black>
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  2. Leadfoot

    Leadfoot 1/2 ton status Premium Member

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    Well is shouldn't be too restrictive and if you are planning on dual inlets, you won't have a problem getting air. If I remember correctly (at least on mine), there is a sensor on the underside of the air cleaner box with a vacuum line running to it. It senses the temp of the carb and incoming air. It controls the vacuum going to the flap which allows warm air from the manifold heat to be drawn to the carb, when it warms up it closes it. You don't "need" it, but it sure makes cold morning idleing and warming up much quicker.

    There is a Right way, a Wrong way, and then there is My way. The latter is usually the most fun! [​IMG]
     
  3. blackdog

    blackdog Registered Member

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    <blockquote><font class="small">In reply to:</font><hr>

    It senses the temp of the carb and incoming air

    <hr></blockquote>
    <font color=black>I've got a throttle body if that makes much of a difference...

    <font color=black> "Where did all these people come from, and how soon can they leave..."
    -OLD 97's</font color=black>
    <a target="_blank" href=http://www.k5.batcave.net>www.k5.batcave.net</a>
     
  4. Kyle89K5

    Kyle89K5 1/2 ton status

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    Honestly, I pulled mine and so no difference. Either in hot or cold.

    Kyle
    89K5
     
  5. Leadfoot

    Leadfoot 1/2 ton status Premium Member

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    I never had a throttle body so I don't know, but I would assume it is a similar principle (but I could be wrong). I would assume it's probably computer controlled rather than vacuum, but like I said I never had a throttle body and the one's I have seen, I never really looked at how their's were set up.

    There is a Right way, a Wrong way, and then there is My way. The latter is usually the most fun! [smile.gif]
     
  6. Itali83

    Itali83 1/2 ton status

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    I pulled mine a long time ago with my TBI no problem. And within in last month, I made a "factory" looking dual snorkle intake. I did notice a little difference with the dual snorkle over the single, and I still have a regular paper filter, I'm hoping I'll feel even more with the soon to come k/n filter. Yank it out and then make it dual intake, it's well worth it and if you do it like me, you make people who know a lot about GM's think it is factory!!! lol
    Ben 87 Jimmy
    <font color=blue>Rust=Bad</font color=blue>
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  7. Bubba Ray Boudreaux

    Bubba Ray Boudreaux 1 ton status

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    Got pics of your intake? By the way, I'm running an open cleaner on my TBI and it does stumble a little when it's cold, but it doesn't stay cold for long.

    Bubba Ray Boudreaux,
    Leader of the Advance Party for
    the CSA revolution in the PRK!
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  8. tim_87

    tim_87 1/2 ton status

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    bubba, just wondering what you did with all the hoses, etc. when you went open air. i have a 87 tbi

    musicman
     
  9. blackdog

    blackdog Registered Member

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    <font color=black> No, I don't have pictures, but I figured what the heck and took the flap out this afternoon (It's only one pin if I ever want to put it back). I can't say if there's any noticable difference, because when your trying REALLY hard to notice something so small, your imagination can play tricks on you. I figure, though, if you do 50 small things to improve performance, eventually they're all going to add up to something real.

    <font color=black> "Where did all these people come from, and how soon can they leave..."
    -OLD 97's</font color=black>
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  10. Bubba Ray Boudreaux

    Bubba Ray Boudreaux 1 ton status

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    The only two things that was that I had on my stock cleaner was the PCV filter/hose and the preheater hose. I kept the PCV hose and filter as is, but zip tied it off to the side so I could keep it. I've seen open air cleaner assemblies that have the eccentric to keep the PCV hooked up, but I'm not into throwing change into something like that. The preheater hose is no longer hooked up. The attachment on the manifold is just a shield, there was no actual hole in the manifold like I thought there would be. I did keep the stock cleaner setup due to smog purposes. The reason for the preheater hose is for warm air to go into the fuel system to help atomization when the system is cold. The door on the cleaner is actuated by a thermostatic doo-hickey that opens and closes according to temp. Now, before I smogged my truck, I pretested it since I had access to a machine at the time and other than maybe a difference when cold, there was no emission amount difference between the stock and open. It's just a visual thing to make CARB happy. But then again, my tech didn't even check to see if I had a cat, though he did say I should think about getting a new one soon. I test again next March so I'm getting a new exhaust system. WOOHOO. If I could afford headers, I would, but can't right now. I'm getting a new cat and Flowmaster 1 Chamber and have it exit in the middle underneath the truck due to a suspension redesign soon.

    Bubba Ray Boudreaux,
    Leader of the Advance Party for
    the CSA revolution in the PRK!
    <a target="_blank" href=http://community.webshots.com/user/mdntrdr1>http://community.webshots.com/user/mdntrdr1</a>
     
  11. dyeager535

    dyeager535 1 ton status Premium Member

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    That valve is opened up by vacuum, controlled by the vacuum switch located (typically) IN the air cleaner. The switch is controlled by heat..when its hot enough, it allows vacuum to close that flap. I'd be surprised if removal of that is worth it. If I'm not mistaken, upon close inspection, you will note that when the valve opens, it blocks off the lower hot air tube fitting, thus preventing hot engine air from entering the air cleaner. Even carbed, running truck without that hooked up has made no difference in driveability, although its been too warm to realistically tell probably.

    Dorian
    My tech/links page: <a target="_blank" href=http://www.dorianyeager.com/index2.html>http://www.dorianyeager.com/index2.html</a>
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