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header options explained please

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by ftn96, Feb 23, 2001.

  1. ftn96

    ftn96 1/2 ton status

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    Im looking at Thorley's and there are some listed with air pump: air injection in manifold, adn w/ or without heat riser.

    Do I need these 2 things for my 90? Andwhats the difference anyway. I understand there a little bit of pre-conditioning the fuel or the air before it goes to cylinders.
    Cna you'll educate me?



    Will work for beer, parts and tools.
    90 Jimi,350/700R4/241/10bolts/4.10's/33's/4"
    <A target="_blank" HREF=http://www.nashvillek5.freeservers.com>http://www.nashvillek5.freeservers.com</A>
     
  2. HarryH3

    HarryH3 1 ton status Author

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    If you have those nice stainless steel tubes going into fittings on the exhaust manifolds at each exhuast port, then you have the air injection system. It pumps air into the hot exhaust stream to help burn off any unburned fuel that's left over. If your state has (or will have) a visual inspection, then you'll need to keep these.

    The heat riser is the little piece that the tube from the exhaust manifold up to the air intake snorkle attaches to. May be required to pass emissions, depending on local regs. It does a couple of things. 1) It helps the engine warm up a bit faster since the thermac in the snorkle will route hot air into the intake when it's cold out. 2) It keeps the throttle body from icing up in cold, damp weather by mixing warm air into the intake stream.

    <font color=black>HarryH3 - '75 K5</font color=black>
    <A target="_blank" HREF=http://ThunderTruck.ColoradoK5.com>http://ThunderTruck.ColoradoK5.com</A>
     
  3. ftn96

    ftn96 1/2 ton status

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    So i should get the ones that have both features?
    In Tn, the just stick the tube up you ass and check to see if you have the stoper valve under your gas tank cap and check to see that you have a CATY. But the heat riser sounds like I need it. And the air injection seems as though it would help with performance a little bit, at least from the way you explained it.

    Hair, you get my follow up post on those camber shims?
    Preciate it.

    Will work for beer, parts and tools.
    90 Jimmy 350-700R4-241-33" BFGs-10 bolts w/4.10's
    <A target="_blank" HREF=http://www.nashvillek5.freeservers.com>http://www.nashvillek5.freeservers.com</A>
     
  4. HarryH3

    HarryH3 1 ton status Author

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    I'd go for both, if your truck already has the air injection system. You'd be screwed if you took the air system off and then the state decided to start checking for it. [​IMG] It doesn't help performance, since the air is injected after the combustion chamber. It just helps the air we have to breathe. [​IMG] It also doesn't use much power to run the pump.

    <font color=black>HarryH3 - '75 K5</font color=black>
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  5. NYC K5

    NYC K5 1/2 ton status

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    i just ordered the thorly headers a few weeks ago. the company is a little back logged so if you need them now order something else. the heat riser isnt important. most people that have heat risers have them wired open anyway, and you cant notice any difference and getting the headers with the heat riser is $60 more. as for the air injectors it depends on what state you are in. if you need a catalic converter get the air injectors, or you can buy a cat with seperate air lines.
     
  6. K5Jimmy

    K5Jimmy 1/2 ton status

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    I have an 89 TBI...no air injection needed...you do, however need the sensor bung on the drivers side....the heat riser doodad can be made or had for way cheap...I just put mine on the pasenger side pipe with a hose clamp when I take it to get inspected (with the stock cleaner and all in place)...after inspection, I take it off and put my KN back on...been doin' it that way for years....JD

    I'm at 10th and Plum....10 miles from nowhere, and Plum out in the sticks....Stuck?...Hell no..I still got some gas left..
     
  7. ftn96

    ftn96 1/2 ton status

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    Alrighty then, thats what I needed to know. But I may change my mind again. My unlce is trying to get me to go carb when I put my new motor in and take all the emmisions and computer crap out. But I dont know if I want to go through all the jerry rigging to do this. Unless I get a different tranny too. But I'll probably just get them with both these options just to be safe.

    thanks gents.

    Will work for beer, parts and tools.
    90 Jimmy 350TBI-700R4-241-33" BFGs-10 bolts w/4.10's
    <A target="_blank" HREF=http://www.nashvillek5.freeservers.com>http://www.nashvillek5.freeservers.com</A>
     

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