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More Quadrajet problems

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Big Muddy K20, Jun 12, 2003.

  1. Big Muddy K20

    Big Muddy K20 Registered Member

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    So now that my new son is 3.5 months old and my wallet is starting to bounce back I decided to start working on my truck again. So after blowing the cobwebs out of it (black widows are not good), I fire it up, runs fine I decide to go for a drive with it, I forgot that before I parked it I put on a fresh out of the box remanufactured Qjet. Well I have similar problems like I've read about others having, The WOT running out of gas bogging, bucking feeling. I also have a similar problem sometimes it will idle and the rpms just start going up, it will hit 1500 sometimes, and if I hit the gas pedal it bogs like it wants to die but then will rev up, it blows out a little cloud of black smoke (rich I think). if I shut it off when it's doing it's idling up routine, it wont start again for a few minutes, it floods I'm assuming. the thing that really sucks is that I spent a few hundred bucks on this carb, and it's doing the exact same thing as the old one did, I think I threw away money on something that could have been remedied by some tuning/adjustment. I'm competent, but I come from the world of holley carbs, I'm not too sure where to begin with the quadrajet. I have a few manuals but they don't really seem to address the symptoms I have.
    Thanks
    Tony
     
  2. dyeager535

    dyeager535 1 ton status Premium Member

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    One of your issues sounds choke related. Are we dealing with an electric choke?

    Anyways, I'd get the vehicle warm, and then I'd prop the choke wide open. Make sure the secondary lockout tang is not engaged when you do this, as it shouldn't be when the vehicle is warm. (choke open)

    Secondary lockout tang is on the passenger side, bottom rear of carb. (for newer Q-jets) There is a pin pushed through the secondary throttle plate, and there is a "dogleg" shaped piece that contacts that pin when the engine is cold to keep the secondary's from opening.

    My friend bought one of the new Edelbrock carbs, and the electric choke was/is always giving him problems, and it sounds like a common occurence on rebuilt or new carbs, at least Q-jets.. Never really had a chance to mess with it for him though.
     
  3. Big Muddy K20

    Big Muddy K20 Registered Member

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    thanks for the reply, my first thought was a choke misadjustment, I haven't looked at the tang on the linkage to see if it's hanging up, but I did pull over when it started doing it's idle up routine and pop the hood, I removed the air cleaner lid and the choke plate was wide open like it should have been, I'll have to go out and look to see if the linkages hang on each other, I am thinking that I probably have to set the float height too, it makes no sense to me that these carbs can be so out of whack and yet they still cap off the idle mixture screws when they remanufacture them...
     
  4. dyeager535

    dyeager535 1 ton status Premium Member

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    If you are getting increasing idle problems, it's not going to be the mix screws. They are "static", once set, they are set, and nothing changes their setting. Junk in the passageway, gas quality, etc., might affect idle, but there is no moving part that is supposed to control idle that moves normally.

    How "wild" is the motor? Just kinda curious.

    If float level is wrong it can spew gas into the air cleaner, that could increase idle. So could bad gaskets. Might want to re-check the 4 carb to intake bolts for the heck of it, as they would help seal the carb seals somewhat, just don't overtighten, that would cause more problems.
     
  5. Big Muddy K20

    Big Muddy K20 Registered Member

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    I know the idle mixture screws are set and forget, I was just commenting on the fact that all carbs I have ever installed, at the minimum I've had to set the idle mixture... the holley on my drag truck, aside from changing the jets and setting the float (holleys are so adjustable) I also went so far as to install the quick change secondary spring kit...to try to eliminate that "my cam is a bit too big and my converter is a bit too tight" bog when it launches...
    It just seems to me that they are doing everything they can to make people take it to a mechanic, seems like a scam, I've never taken something to a mechaninc before, I've done everything myself or with the help of a friend, usually by myself though, and late at night it seems.
    as for the motor in my big truck, it's stockish goodwrench motor w/ comp xe252, roller tip rockers, performer intake and headers, msd 6a box and wires w/ stock but recurved hei. I did everything I could to enhance performance, yet maintain a good idle with alot of vacuum and the qjet is my attempt at running on sidehills and steep inclines while idling or just above idle in low when I'm wheelin' it. The double pumper worked great when it was a mud truck (nail it in the mud and all was good, but it sucked for trails), but it is slowly but sureley becoming a rock crawler/trail/assault vehicle, plus I'm sick of all the mud that gets underneath and inside it...
     

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