qjet is 1 of the hardest carbs to set up out there.. You gotta start at the choke pull-off and work your way through the whole carb:
Engine cold, 1/8" drill bit opening on the choke plate, use a hand vacuum pump on the choke pull-off. Do not start engine.Adjust the choke plate by bending the linkage carefully that pulls it open. Check to see that the dog leg linkage is holding the secondary throttle plates shut snugly, adjust linkage to those by bending carefully as necessary. The choke pull-off controls idle speed until choke is fully opened. Adjust screw until primary throttle plate opens ever so slightly. Main idle screw on carb body should NOT be touching the throttle linkage yet. Turn mixture screws all the way in and back off 1.5 turns. The idea here is that that choke holds the secondaries shut till engine is warm, and it kicks the idle up a bit till it warms up. The choke pull-off is the key to the whole carb, its the computer. Start the engine. If you're way off on your choke pull-off idle setting, stop it immediately and make adjustments quickly before engine begins to warm up. It should step down a couple times until the throttle linkage reaches the main idle screw. Choke pull-off runs on manifold vacuum, not ported. Make sure the pull-off holds vacuum, just because its new dont mean its good. Make sure PCV valve, power brake booster check valve and booster itself are good. If its an automatic check vacuum hose to trans for fluid and/or vacuum leak. Check vaccum amplifier very carefully and under dash heater controls. It sounds like you have a vacuum leak and the carb is running on the main circuit instead of idle circuit. Start engine and get your idle on choke to about 1500 or so quick as you can, adjust choke plate slightly for smoothest running position.watch for the choke plate to slowly open on its own, do not rev motor or touch throttle. When choke is fully open,bump throttle and engine should drop down to idle on the main screw. Set base timing at correct idle speed with vacuum line off and plugged. Now climb up on motor and look down inside carb while engine is idling, if you see it slobbering drops of fuel, your rods are up off their seats most likely. Bend linkage accordingly. Secondaries should not open until choke plate is all the way open. Having fun yet? You cant see the inside of the secondaries while its running, but you can see the thing theyre hooked to and tell if its raised up as well. The idea here is the rods are all the way down on their seats until you step on the gas, then they allow the vacuum created inside the barrels to pull fuel through the passages into the barrels. The accel pump gives it a little headstart on the process. It should start to squirt the instant you give it the slightest gas, and continue to squirt all the way through the acceleration process. We dont want the secondaries opening too soon, so the pull-off controls that too. That should keep you busy for several days.
Idle circuit, then primary circuit, then secondary circuit for full throttle.
Oh and by the way, Qjets bought rebuilt these days tend to be way out of adjustment and have parts missing because very few people are left that actually know how to work on them. You might be better off to put the base plate off the new carb on your old one if it looks pretty much the same, but lots of adjustments to make and a special tool to hook up the choke rod lol.. If it were me, I would just put a new Holley 600 electric choke single feed vacuum secondary on it and be done.. As far as the whole float thing, its not a big deal. Either its flooding and youll see that very clearly lol or it will fall on its face when you tromp it. If it isnt doing either one of those things, youre close enough on the float level, needle, and seat.
