My 84 has a ccc quadrajet, but all the computer has been taken out lol. NOw for the prob. Runs fine, can give it all the wants until you mash it. You can feel it in the pedal. You can go up to about 3/4 throttle crisp and clean, then when you get to that "stiff" feeling in the pedal and try and go past that it will stumble for about a second or so and pick back up like it never happened.Gets kinda annoying, anyone have a suggestion? thanks.

 

ok, first things first, a computer controlled q-jet with no computer won't work well at all. I tried it for about a week, then realized those plugs on the carb were actually necessary to get better than 4mpg.

so that's your first problem, if you were serious.

If not, your secondary air valve tension is the absolute most common cause of a bog on a q-jet, and sounds like what you're experiencing. Plus it's an easy fix. See the main page on tgo for instructions for that.
www.thirdgen.org/qjet or something like that.

 

Oh yeah. You CAN NOT RUN A CCC QJET WITHOUT THE COMPUTER. The enrichment is controlled by vacuum on the old non CCC Qjets. On the CCC it is controlled by the computer ONLY. Either hook the ECU back up or get a non CCC Qjet.

 

yeah it does get pretty lousy gas, and the bog, but other than that it runs fine. The page for the air valve says it cant be found.

 

also, are the back butterflies suppose to open under ful throttle?? Cuz the dont open at all. These are the secondaries on the q-jets right?

 

whoa whoa, first things first. You CANNOT run a computer controlled carb and computer controlled carb with no computer. FIX THAT FIRST! Seriously! You will be miles ahead when you get that fixed ok?

A non-cc q-jet and distributor to match can be found at a junkyard from an old lady driven caprice/cutlass/monte carlo etc etc. Find the one with a beautiful interior and low miles, and snag both of those off it. Probably get the pair for under $50.

then go onto to fixing the problems. Your secondary air valve opens under heavy throttle, *AND* under load. But not when you sit there revving the car, watching the butterflies. You have to be moving, loading the car. So if you actually want to see the butterflies open, well you gotta find a damn brave guy to lean out the passenger window while you go WOT..

 

well like i said, it already has a non comp controlled distributor on it, and ima get on top of the carb as soon as possible, but where is the air valve adjustment on it?

 

pic of carb

above, and to the right of that light green arrow. Looking from the passenger side (left in this picture), you'll see a spot for a small flat blade screw driver. That adjusts the tension, but first you need to loosen the lock screw. Right below that small flat blade screw, is an allen head set screw, feel for it, it's hard to find. Once you find it, put the flat head screwdriver into the slot, and relax the allen key. Then you should be able to twist the screw, back it off until 0 tension, then "tighten" it 3/4 of a turn or so. Lock the nut.
You probably don't even need to do this though.

As 327 mentioned, you'll be running full rich all the time, it'll be sluggish, and get bad mileage, until you swap out the carb. Don't even bother trying to tune it, it's impossible to get that running halfway decent.

 

well, it just so happens that i remembered that my cousin took the jet of his 83 chevy truck also with a 305, so i called him up and he let me have it for 10 bucks. He had rebuilt if about 3 months before he decided to put the demon on it that he has now. So i brought it home, swapped her out, made sure i didnt have any leaks of any kind. The car is really responive now, gets a lil better mileage, and i can tell it has more power. But its still doin that stumble when i smash it at about 3/4 or so throttle.

 

ok then, now you can adjust your AV tension, that's probably the source of your problems. Once that's setup right, you can play with secondary rods and hangers, it might be going lean/rich when you get to that point, hence the bog.

 

Is the stumble momentary, or lasts as the RPMs rise? If just momentary, you may need to adjust the AV, change out the rods and/or hanger, or all three. If it lasts, then you need rods and/or hanger.

 

It's been awhile since I've worked on a feedback Q-jet, but if I remember correctly the ECM turns on and off the voltage to the electric choke based on closed loop and open loop operation,right?
If so then removing the ECM makes the electric choke inoperable and therefore the mechanical "secondary lockout cam" is engaging the secondary shaft pin (see pic)


Becasue the choke is not unwinding in the housing and not kicking the lockout cam free of the pin(circled in RED).If this is the case, and both carbs you're using have the same electric choke stove,then it would reason that the problem stayed with the next carb.

It just sounds like from your description what a mechanical secondary feels like, in the pedal, when it's locked out. It's as though the pedal is almost pushing back. That would also explain why it bogs too, the primary system can't supply enough fuel and it would take a moment for the engine to level out.

BTW, don't confuse the upper secondary flaps(air valve) with the secondary flaps down below, those are the ones that need to have full range of motion before the upper ones open.

That picture is of an early 80's carb, but if I remember the feedback Q-jets have the same lockout mechanism. It has the hot air choke stove rather than electric but the lockout mechanism behind it is the same.

The quick fix here is to bend that secondary throttle shaft pin out of the way of that dog leg cam so it can't stop it's travel.

...

 

the stumble is just momentary, whenever i smash it nomatter what speed im at. Also i tried adjusting the av a bit, and i didnt seem to help.Iturned it out until it didnt have any tension on it, then retightened it 3/4 turn and tightened the setscrew. Do the flaps need to be loose or stiff, or inbetween or what.Also, when should the secondary butterflies open, around 3/4 throttle right? I was wondering if i made em kick open earlier if that would help, so i too a zip tie and put around the lil metal peice that hits the other little metal piece(not a much of a tech person here) that opens em up, but that just made it worse.Ive been thinkin of just getting a new carb, cuz i have a performer rpm intake just lyin in my floor waiting for a home to, but im afraid it wont fit under the hood, thats why ive been tryin to get the bugs outta this one. Thanks for all your help guys, much appreciated.

 

Get a new choke pull-off, or reconnect the linkage to the AV if it's been removed. You need both it and the AV tension adjusted properly to avoid that AV opening bog.

 

mine has none of that on the side of it, just the secondary shaft with the little cotter pin.
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what would happen if i just too off the back butterflies, so when the bottom butterflies open up, its all ready a straght shot to them.I had to do this to the butterflies on the front barrels when i got the car beacuse the butterfies werent stayin open for some reason, so i just yanked em off, but thats a lil different than doin this.

 

beside the lil av adjust screw, what is that little linkage, cuz mine has nothin connected to it.

 

your carb in stock condition will run the absolute best, compared to any bastarization of the carb you can dream up.

the linkage which goes to your secondary air valve (where you adjust the AV tension), goes to your choke pulloff.
In the picture that I linked to, the choke pulloff is pointed to with a yellow arrow. Make sure you have one.
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here's another picture for you.


yours should look pretty much like that.

 

mine has absolutely none of that on it.