First off, I apologize if this is a topic that has been covered a million times. I can't seem to get it right. I am good at making it much worse though. Life is frustrating when you're a carb newbie and there isn't anyone local to show you some things in person. (I'm actually debating ditching the choke altogether as it is the source of ALL of my current carb problems - I think) Okay, first things first, its basically stock Chevy 283 with a M4ME reman Quadrajet on it. Has an electric choke. Just put the carb on about 2 weeks or so ago. Once it s warmed up, it runs great. Really well. Great throttle response and no hesitation at all. I set the timing for 10 BTDC, mainly on the suggestions of others, seems to run ok there. I also adjusted the idle mix screws for max vacuum the other day. But that timing setting isn't sacred, I can change it if need be. What I can't seem to figure out how to do properly is get the choke set up and functioning normally. The more I read on the Web, the more confused my pea brain gets. With the key out, and the engine overnight cold (well as cold as you can get in Florida) the choke is all the way shut. All the way shut seems to be its natural state unless its been running recently. I assume this is normal. However I will say that the car DOES NOT like to start with the choke like that. I would assume that when it fires, the fast idle is supposed to take over and the vacuum device on the choke linkage pulls it open a little bit. Well, I haven't been successful at setting my fast idle speed - I've followed various instructions I've found, but when the engine first attempts to speed up it sounds God awful. Like it has a string of firecrackers going off in the tailpipes, and it shakes like a bowl of Jello in an earthquake. It smooths out eventually, but then its idling way too fast. Today I manually moved the mechanism so it allowed curb idle. With the Edelbrock I had years ago, tapping the throttle would actually deactivate the fast idle - but I guess on this one it puts it back in fast idle mode. Even if its warm. Nice surprise that was, pulling out of my driveway. So, for now, I turned the fast idle adjustment screw all the way out so its not making contact anymore, and I just hold the choke open for a bit by hand until the engine will idle smooth on its own, which hardly takes any time at all. Seems like of strange that doing the exact opposite of what the choke is supposed to do makes the engine start and run better. But on a colder morning, that might not be the case, and its not really easy to reach the choke from inside the car....and having to get out, pop the hood, and run the engine while holding the choke open for a bit doesn't appeal to me when I'm trying to go home from work. So I'm guessing I have multiple problems, and I just need to start over from the beginning. That said, can anyone out there explain how to set this thing up - sort of like a Quadrajets for Dummies, if you will? I know it can be done, I had an 80's C10 with this same model carb that started and ran like a fuel injected car. Just takes someone smarter than me to set it up. Thanks in advance.
".......... With the key out, and the engine overnight cold (well as cold as you can get in Florida) the choke is all the way shut. All the way shut seems to be its natural state unless its been running recently. I assume this is normal. However I will say that the car DOES NOT like to start with the choke like that.............." Unless I misunderstand, this does not sound right... In the AM, the choke should be open, as it was when you put the car to bed. Only when you step on the gas to "release the choke" should it close....
Jeff, silversink and scrappy - that's what I will most likely and up doing, but we'll see if I can get it work as-designed first. Fenders - what you say makes more sense to me than how mine is currently acting. I've read about hitting the gas (engine off) to "set the choke", but it never made any sense as mine is always "set".
The carb was "re-manufactured" by who? That sounds like the first problem..... 2) From what it sounds like, the choke is either defective, non-functioning, or incorrectly adjusted. So, after the engine warms up. Let's say after 10 mins, is the actual choke blade open and does it stay open by itself? a) please describe your starting procedure when engine cold. When engine warm (within 2 hours of last running). b) You mentioned the vacuum devices (they are choke pulloffs) on the choke linkage. And yes, they are supposed to crack the choke open just a little to prevent to the engine from running too rich. Do these pulloffs open the choke when you first start the cold engine and if so how much? c) Just to make clear, where are you adjusting fast idle? The adjustment screw is near the bottom of the carb below the level of the choke housing, NOT on top near one of the choke pulloffs (if you have two pulloffs). i would not necessarily recommend removing the choke mechanism at this point because you lose hi and mid step idle which i feel is important. You could remove the choke blade only, but i think that wouldn't solve your problems at this point.
The carb wasn't rebuilt by me, it was by a large company. Yes, that may be part of the problem, but I'm hoping I can rule everything else out first. 2) C10, I'm willing to bet its very incorrectly adjusted. After the engine is warmed up, the choke blade is open and remains open on its own. In fact, I can let it sit for 2 hours or so (maybe more, never tried), and fire the car up without any issues. The choke does gradually close itself as the engine cools off, hence if I let it sit overnight it closes itself fully again, and I'm back in this mess again. a) my cold-starting procedure is to step on the gas twice to squirt some fuel, and crank the ignition. Sometimes it takes more throttle while cranking to fire. This worked a lot better on my old carb, which had no choke, so I am not too sure what I should be doing with this one? (If the engine is warm, I just hit the key and the engine barely turns over before it fires and I don't have to touch the throttle at all) b) I'll have to check on the pulloff function tomorrow after work. If I did it now I'd have upset neighbors. c) I'm adjusting the fast idle using the adjustment screw under the choke housing. I don't think I have another one up higher. I do appreciate the help so far.
How fast does it idle now when you first start it? Do you have a tach? i just looked at carb i had on the shelf. Having the fast idle screw all the way out can definitely cause the choke to close on it's own if the engine was warm when you shut it off. It should never do this on it's own. With the screw out, the fast idle cam follower(that lever that "rides" the fast idle cam) is not making firm contact with the fast idle cam letting the choke close by itself as it cools.
Try when it is cold and choke is closed with a had vaccume pump or a long peace of hose hooked up to the choke pulloff apply vaccum to the pulloff and adjust the pulloff to were you just slip a 1/4 in drill bit in the air horn between the choke flap and the choke horn at the top edge of the choke. Now set the fast idle screw to were it just opens the throttle when the fast idle cam is on the first step. Now when you start it cold just step on the throttle one time if it starts and dies then back off the pulloff a little tell you get happy.
C10, yep I have a tach. Before I backed the fast idle screw all the way out in a fit of rage, it would attempt to idle fast when first started. I say attempt because it was sputtering and shaking like crazy and really wanted to die. So I don't know for sure what RPM it was trying to idle at, because it was all over the place. It eventually smooths out, but I don't remember what RPM its at. Its pretty high. saltflats, I'll hunt down vacuum pump and try that. If anyone knows how to get a good baseline setup with the fast idle (or anything else I need to do) that would be great.
I think that if you adjyst the fast idle screw to just open the throttle one the first step would be pretty close it may be a high idle when it first starts but when the fulloff opens the choke a little you tap the throttle and it should drop down to something that you could live with. You do need to make sure that the fast idle cam falls down when the choke opens you can test this with the engine off by opening the throttle and close the choke by hand and let the throttle close now by hand open the choke holding it open open the throttle a little and see if the fast idel cam falls down. I have seen many Qjets that the fast idle cam would hang up thay use little ruber seal on the shaft that can give problem.
Oh you can just get a peace of hose and suck on it to set the choke pulloff if it does not work by that method the pulloff is probaly bad.
you should by adjusting the choke cover cold so that the choke blade just touch the tower then turn cover 2 more notches then adjust the pull off, fast idle set on high step at 2500 rpm hot there is another adjustment for the timing for the steps which normally doesn't need to be adjusted. try this and you should be close. the float height also affects the choke
I never run a choke on my cars, and they start at -40 without one. Just pedal the gas and nurse it for a minute after it fires up.
I am not sure if the choke is all of your problem.I have a feeling the well plugs are leaking.It is a common problem with Q-jets.I have never seen a factory reman adress the issue.
If you pull off the base plate and clean the plug area you can seal the plugs with jb weld.Just make sure you let it sit for at least 12 hours before putting gas in it.
Good point on the well plugs. You know I never use a reman carb thay scare the hell out of me you know that person has no clue about what he doing IMO.
I never have gotten any reman carb to work correctly right out of the box.Most of the time i have had to take them all the way apart to get them to work right.
I am no quadrajet gguy so i can't give you advice as far adjusting it but a common problem for engines taht have had electric chokes added is that they pull keyed voltage from the coil and that won't let the choke work right because of the ballast resister or resistor wire. The choke needs its' on 12v keyed source.
Bit late, but I think I got it close enough to work. Choke was set pretty tight from the rebuilder, loosened the 3 screws and turned the black housing to the right a bit, and now it seems to be working properly, or close to it.
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