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Edelbrock Q-Jet and general carb questions

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by mplogic, Jun 13, 2002.

  1. mplogic

    mplogic 1/2 ton status

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    Ok, probably been asked before, but couldn't find it down below. My bro has a 77 Jimmy and the old Q-Jet is on it's last legs. Was looking at an Edelbrok Performer Q-Jet as a repacement. Do these work as well as the original Q-Jets in off-road situations (angles, etc.)? Is it still possible to get the original (Delco?) Quadrajets new? Also, I've got a Carter style Edelbrock carb with a Performer manifold that came off another truck. Are these any good for off-road use?

    Appreciate the advice!
     
  2. dyeager535

    dyeager535 1 ton status Premium Member

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    First off, let me say, rebuild the Q-jet. At worst, you screw it up and a bad carb now doesn't work at all, for the cost of $20. At least you'll know how they operate internally.

    The Edelbrock Q-jets should be as good if not better than stock Q-jets, as I remember they claim to have made some improvements to them. Never had one apart, can't comment. You also pay for them.

    GM was selling carbs awhile back, not sure if you can still get them. If you can, I'm sure they are as proud of them as Edelbrock.
     
  3. MudbogAD

    MudbogAD 1/2 ton status

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    Personally I wouldn't run a carter if it was given to me. /forums/images/icons/smirk.gif If you rebuild the q-jet, it will almost be as good as new.
     
  4. Blazer_Boy

    Blazer_Boy 1/2 ton status

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    Make it yourself! There really isn't anything too special about them. All of the parts will interchange between the original and the Edelbrock ones. They have an 850 CFM model that is a little bit special, but thats it. What you do is get Edelbrock rebuild kit #1921. They give tons of parts in the kit as opposed to parts store cheapy kits.

    You basically want to calibrate this thing just like the Edelbrock one and you will have the same carb. You want 50M primary rods, .073 jets, and DR secondary rods. Yes I know its a confusing mess of numbers, but if you know a little, you can do it. All of the parts have the numbers or letters stamped right on them.

    Look at Summit or Quadrajet.com to get these parts. Just call and tell them what they want and I'm sure they'll lead you in the right directions. You can buy all those parts on their own instead of having to get a calibration kit. Personally, I would be glad to have saved $300, keeping the original, and knowing you did it yourself.
     
  5. 91K5

    91K5 1/2 ton status

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    I've heard good and bad about the Edelbrock Q-jets. Personally I'd use the stock one and rebuild it, or even better yet find a pre-1975 as they are a little more tunable. A stock Q-jet is a wonderfull all around carb if it's tuned right IMO /forums/images/icons/smile.gif
     
  6. mplogic

    mplogic 1/2 ton status

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    Thanks for the input guys. I think we're going to do a rebuild for now and save up for one of those new Holly Truck Avengers (or maybe even FI). /forums/images/icons/smile.gif
     
  7. dyeager535

    dyeager535 1 ton status Premium Member

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    Primary metering rods/jets, power piston spring, float level, secondary metering rods and hangars, and secondary air valve opening rate are things that are specific to the engine the carb is installed on.

    Each and every one of those was picked by GM to meet the purpose the vehicle was intended for, while still getting fairly good mileage and later on, less emissions. If you mess with them, and expect it to work well without testing, more often than not, you'll end up with problems.

    If you are going to change that stuff, you are going to need a big supply of spare rods/jets/hangars, and spend a lot of time tuning it.

    I went through 4 secondary hangars and about 6 sets of secondary rods tuning, after changing the cam in my car, using the original Q-jet for that engine.

    Assuming the carb in question here is original to the motor, rebuild it as is, without changing the "hard" parts like rods, etc. Primary side governs economy and cruise, and I *guarantee* GM spent a lot of time getting that carb setup for that vehicle so those two criteria were well met. Since thats all the primary is for (essentially) leave it be. if you want more power, fiddle with the secondaries. If you change engine specs, like cam, exhaust, etc., you may need to mess with rods/jets and the like. The secondary side, well, you can play around with that a lot. : )

    I just don't want him getting confused on what *needs* to be done, as opposed to what *can* be done, which starts to get much more in depth, especially for someone that hasn't even had one of these carbs apart yet.
     
  8. Blazer_Boy

    Blazer_Boy 1/2 ton status

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    </font><blockquote><font class="small">In reply to:</font><hr />
    The Edelbrock Q-jets should be as good if not better than stock Q-jets, as I remember they claim to have made some improvements to them. Never had one apart, can't comment. You also pay for them.


    [/ QUOTE ]

    Well now the part selection can't be all bad in them dyeager. I just told him the recipe for the edelbrock q-jet that is listed for his application. He could do that instead of spending all that money for an Edelbrock OR he could just put in a basic rebuild kit. The Edelbrock rebuild kit sticks with almost all of the GM specs. Heck, even the diagrams and pictures in the directions are from GM manuals /forums/images/icons/laugh.gif
     
  9. dyeager535

    dyeager535 1 ton status Premium Member

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    No I'm not saying its bad I'm just saying its not *right*. Sure, you can run 13:1 mix and it will run great, but your mileage will suck. My 307 ran extremely strong, yet it got 10MPG.

    There wouldn't be this many primary rods http://www.dorianyeager.com/qjetprimaryrods.html and this many secondary rods http://www.dorianyeager.com/TablePics/qjetsecondaryrods.jpg (not to mention all the hangars and power piston spring combos) if one size fit all.

    If I can swap an E-brock carb on my truck and get same as or better mileage with no work/mods, I'd agree with you. Anyone wants me to test, feel free to send me one lol.
     

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