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Chevy 305 in el camino sounds like boat motor

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by weisel, May 9, 2001.

  1. weisel

    weisel 1/2 ton status

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    I was helping my brother fix his starter the other day and noticed that on his factory exhaust system, there is a weird vacume controled thingy on it. It lookes like a vacume controled diaphram moves a lever and spins a shaft in the tube which lookes like it has a throtle plate type thing in it. Try to imagine a vacume controled choke on the exhaust pipe! and it dosn't even have a hose hooked up to it. I just wanted to post this and see if any one has seen this, what is happening in it exactly, and what is it for?

    Insurred by Smith & Wesson
     
  2. muddin4fun

    muddin4fun 3/4 ton status

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    Oh gawd! I know exactly what it is! I can't think if the name right now!!!!!! ARRRGGGG!!!!! The thingymagig, right!!!!! GRRRR!

    [​IMG]
    <A target="_blank" HREF=http://k5chevyblazer.homestead.com/home.html>http://k5chevyblazer.homestead.com/home.html</A>
     
  3. weisel

    weisel 1/2 ton status

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    ya, the thingamajig...do you know what it dose?

    Insurred by Smith & Wesson
     
  4. muddin4fun

    muddin4fun 3/4 ton status

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    heat riser valve!!!!!!!! I think? I dunno what it does. Prolly something when the motor is warming up.

    [​IMG]
    <A target="_blank" HREF=http://k5chevyblazer.homestead.com/home.html>http://k5chevyblazer.homestead.com/home.html</A>
     
  5. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    I believe its only purpose is to block off exhaust on one side to force hot exhaust through the heat riser passage when the engine is cold.

    Bad Dog

    85 K30 CUCV, 350 TBI, TH400, NP205, D60/C14, 4.56 Locked
    Soon: 4" lift, 40" tires, massive cutting, shorter wb and rear overhang.
     
  6. CaptCrunch

    CaptCrunch 1/2 ton status

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    I think baddog and mudd'n have nailed it! 2 points!

    [​IMG]
    1987 Chevy K5 Blazer- 350 TBI
     
  7. Blazer79

    Blazer79 1/2 ton status

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    My Blazer had one of those. I couldn't believe it when I saw it. Fortunately it was stuck in the open position. I removed it and now I have a set of Flowtech Headers [​IMG][​IMG]

    <font color=blue>//////
    <A target="_blank" HREF=http://blazer79.coloradok5.com>http://blazer79.coloradok5.com</A>
    </font color=blue>[​IMG]
     
  8. weisel

    weisel 1/2 ton status

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    it dosn't get cold enough to need a heat riser here so i will just wire it open. thx a lot for the info.

    Insurred by Smith & Wesson
     

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