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Old 01-02-2003, 09:22 PM
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Post Quadrajet choke adjustment questions

One book says to turn therm. cover counterclockwise to the 2NR mark.(I assume thats 2 notches from the center on the rich side). Another book says to turn CCW until choke plate closes completely, than turn CW until choke plate opens 1/16". These are two considerably different settings in my case.

(Side note: please someone verify that the rich side is the side MORE counterclockwise from center...<--rich center lean--&gt

Another problem with the second method is: My choke plate does not close completely. If I bend the rod so it does, it messes up my other setting(using .120 gauge against plate and air horn while on second step of fast idle cam). I can't have it both ways.

[ January 05, 2003: Message edited by: MopaRV ]</p>

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Old 01-03-2003, 03:40 PM
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Wait untill the engine has been sitting all night and then adjust the choke so that the plate closes as far as the linkage will let go, then start the thing and drive for 30 min. or so and lift the hood to see where the choke sits at operating temps. If it looks fully open than leave it. If it looks partly closed than adjust so that you get in the middle of the two setting and try that for a few days and see if it works right for you. Chokes don't always have to be shut tight in order to richen mixtures for easier starting.
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Old 01-03-2003, 04:25 PM
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not all Qjs set the same some cw some ccw. Trile and errow works every time GOOD LUCK
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Old 01-03-2003, 04:31 PM
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yeah what I ended up doing is just loosing the damn thing and rotating daily for like a week... it still give me trouble every once in a while...
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Old 01-05-2003, 03:21 PM
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It looks like the choke is fully opening too early, so it backfires all the time when I throttle. There is a 1/8 gap after the first couple of minutes or so, then quickly opens. It idles REALLY rough or stalls, so I close the choke plate by hand until there is a 1/4-5/16 gap or so, to the airhorn and it smoothes right out. Any more or any less it idles rough. It seems to "need" to be in that position for the first 10-15 minutes. Even after, if I partially block airflow, it idles a bit smoother. Should I turn the mixtures screws out a bit to richen it? (Again, one book I have says yes, another book says the (2)mixture screws have nothing to do with idle mixtures or performance.) By richening, can I expect even worse gas mileage than the 5 mpg I'm getting now?
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Old 01-05-2003, 05:37 PM
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In my understanding, and in setting up my Q-jet, I only adjusted the ilde screws when the engine was hot. I kept turning the choke ritcher a little at a time until I got it to warm up correctly. The problem sounds like it's still in the choke - if you cannot adjust it any more, maybe the spring is shot ( too weak ) and is coming off too early. I have a buddy that went thru all that and replaced the choke unit & bingo, problem solved.
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Old 01-05-2003, 05:45 PM
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You should adjust the idle mixture screws only after the choke has completly opened and the engine running at normal operating temps. Then leave em alone because changing too many things at he same time will only make you lose track of the settings. Sounds as if the choke is still maladjusted but not at the housing but the rods and linkages are still out of wack or the vacuum signal is too low at idle causing the choke to open to soon or three, the motor is way too lean at idle and the choke is being used as a crutch too fix the lean cold idle situation. Take a real good look at the condition af you're carb and make sure its still a good one. The q jets have a lot of small circiuts that are'nt hard to plug with dirt. Maybe swap it and see what that will get you. What are we working on here?
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Old 01-05-2003, 06:14 PM
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Its a Q-jet off a '79 cadi 425 on my Dodge 440 motorhome. Yeah, I know, not exactly a hot rod, but if anybody knows this stuff is Rodders, so here I am. I do have another carb(same year/make) that I overhauled for the first time, but I'm experimenting/learnig with the one I have on. At least I know that one will get me from here to there, but I'm almost ready to put the other one on. I can turn the therm coil, THAT, I understand. The carb on, has no mark, so its a guess. The overhauled one has a mark. I'm still a little overwhelmed with the linkage, vacuum break, fast idle settings. It doesn't help when q-jet specific books give me different answers and no real order to do some stuff. That's why I have to ask what are probably simple/stupid questions to most.
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Old 01-05-2003, 07:26 PM
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Get the idle mixture right with the engine hot and then tune to get the choke right, no book will have the perfect settings/solution. Trial and error is required for perfection, those other settings are for completely stock engines and are specific for each application.

Your doing the right thing just not the right order. Mixture first.
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Old 01-08-2003, 10:25 AM
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Getting a wrench or screwdriver to adjust mixture screws on the engine is next to impossible. And definitely impossible for fast idle adjustment. How many turns of the fast idle screw once throttle plates close is a good prelimenary bench setting? (Books say use manual or underhood label for that, which I don't have access to.)
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Old 01-17-2003, 08:30 PM
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Damn chokes! I have a cable, with a knob, runs thru the fire wall....
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Old 02-19-2013, 08:27 PM
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Quote:
Originally Posted by MopaRV View Post
Getting a wrench or screwdriver to adjust mixture screws on the engine is next to impossible. And definitely impossible for fast idle adjustment. How many turns of the fast idle screw once throttle plates close is a good prelimenary bench setting? (Books say use manual or underhood label for that, which I don't have access to.)
Get one of these.
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