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Will a Carb from a 86 k-5 work on a 85

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by MuddNutz, Aug 24, 2004.

  1. MuddNutz

    MuddNutz Registered Member

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    My 85 305 powered K-5 needed a new carb so I bought a carb of a 86 model not realizing that an 86 was a computer controlled carb. I took it to a local carb shop and they said it wasn't a problem so they rebuilt it and installed it on my k-5. It runs good, just deisels bad when you shut it off. I took it back and the guy said it deisels because my truck doesn't have the computer connection it needs to work the carb right. Long story short I will never go back there. Are they right am I just SOL with this carb or can it be made to work?
     
  2. pauly383

    pauly383 Daddy383 Staff Member Moderator

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    [ QUOTE ]
    I took it to a local carb shop and they said it wasn't a problem so they rebuilt it and installed it on my k-5

    [/ QUOTE ] [ QUOTE ]
    I took it back and the guy said it deisels because my truck doesn't have the computer connection it needs to work the carb right.

    [/ QUOTE ]

    The guy said one thing and took your money , then he says another when you go back . i would call the better business bureau , as you just got ripped off . It would off been better for him to say return it and get the right one /forums/images/graemlins/k5.gif
     
  3. smprider112

    smprider112 1/2 ton status

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    try running either super or premium gas...mine does that on reg gas /forums/images/graemlins/thumb.gif
     
  4. dyeager535

    dyeager535 1 ton status Premium Member

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    The fail mode on those carbs is full rich on the primaries. It will NEVER run right, and you will be wasting huge amounts of gas. BTDT. My car SEEMED to run ok, but with OD and a 307, it should have done better than 10MPG on the freeway /forums/images/graemlins/smile.gif

    I'd take those guys to small claims court.

    You MIGHT be able to resell that to someone with a GM car, like a Monte Carlo or Grand Prix, as it will have the right fuel line fitting for those cars. Not positive all the vacuum fittings are there, but I suspect they would be.
     
  5. R72K5

    R72K5 Banned

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    yeah the EST/ESC carbs have ECM contrlleld misxture solenoid, thats what the wires on the carb air horn assembly on top are for, some models have a third wire, like in 86 for the c-10's i know, it goes to a temp sensor in the intake i know,

    emissions components varied considerably upon model and year and where its being built for, IE california or high altitude, or if for low altitude, or overseas or whatever, not ever engine in a year and particular model got identical emissions components, even if were built one after the other on the line,

    all depends on other things like tranny ordered and axle ratio and so on and so forth, its prett complicated but GM kep track of it at the time of assembly run,

    the ECM carb is useless to you unless you convert your 85 all back to ECM controlled spark timing again, which im sure you dont want ot or dont have to where you are or youd have been swapping the 86 carb on.


    good luck
     
  6. Blue85

    Blue85 Troll Premium Member

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    That's just not going to work. /forums/images/graemlins/frown.gif You need the right carb. The distinction between computer carb and regular was not just by year. I think in general, the CCC units were only on cars and California trucks. You don't want one, even if you could get all of the other parts to make it work.
     
  7. trailblazer86

    trailblazer86 1/2 ton status

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    Do you have a picture of the carb?
    I have an 86 and the carb is not computer controled. It does have electrics that only control the size of the shot from the accelerator pump.
    If this wire is not connected you just get a little larger shot from the accelerator.
     
  8. pauly383

    pauly383 Daddy383 Staff Member Moderator

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    [ QUOTE ]
    I have an 86 and the carb is not computer controled. It does have electrics that only control the size of the shot from the accelerator pump.
    If this wire is not connected you just get a little larger shot from the accelerator.

    [/ QUOTE ]

    Wouldn't that be a computer controling that , I don't seem to recall any passive electronics to control anything on a Quadrajet except the choke and the idle bump up solenoid /forums/images/graemlins/thinking.gif
     
  9. 84_Chevy_K10

    84_Chevy_K10 Banned

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    [ QUOTE ]
    [ QUOTE ]
    I have an 86 and the carb is not computer controled. It does have electrics that only control the size of the shot from the accelerator pump.
    If this wire is not connected you just get a little larger shot from the accelerator.

    [/ QUOTE ]

    Wouldn't that be a computer controling that , I don't seem to recall any passive electronics to control anything on a Quadrajet except the choke and the idle bump up solenoid /forums/images/graemlins/thinking.gif

    [/ QUOTE ]

    No. Some carbs have a dual stage accelerator pump that has some wires running from a temperature switch to the carb. I think that an engine will run fine without it even hooked up though, I think it is designed to give a bigger shot when the engine is cold to keep it from studdering on hard acceleration when the engine is cold.

    You shouldn't be hammering on it with it cold anyway, so I doubt you'll notice the difference. /forums/images/graemlins/thumb.gif
     
  10. pauly383

    pauly383 Daddy383 Staff Member Moderator

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    [ QUOTE ]
    I think it is designed to give a bigger shot when the engine is cold to keep it from studdering on hard acceleration when the engine is cold.


    [/ QUOTE ]

    OH ...so the easy solution is to wait until the choke unloads before you drive , to avoid that ( edit : sarcastically said , refering to older carbs , then look at the NEXT sentence ). So they engineered it ( the said piece of the carb ) to accomodate the people who don't warm up . I am glad my Quadrajet works real well , and has none of that . /forums/images/graemlins/k5.gif /forums/images/graemlins/k5.gif
     
  11. trailblazer86

    trailblazer86 1/2 ton status

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    No. The choke has nothing to do with the thermal switch that controls the accelerator pump charge.
    I have seen no adverse effect with this wire disconnected.
    Maybe you could drill a new hole in the pump mechanism to shorten the travel of the plunger. That is a lot of work for no real gain though.
    Get an old Quadrajet and a good manual, spend some time taking the carb apart and putting it back together. Assembly is the only difficult part of a Quadrajet and that is easily overcome with experience. (Take you time and be gentle)
    Now you can rebuild/refresh your carb. Changing some of the jetting and some modifications on the idle circuit make a very drivable vehicle.
     
  12. pauly383

    pauly383 Daddy383 Staff Member Moderator

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    Fixed my post for you so you'd know from context , I wasn't meaning the choke in that way /forums/images/graemlins/k5.gif /forums/images/graemlins/k5.gif
     

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