RE: QJet Adjustment Help
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RE: QJet Adjustment Help - 7/28/2007 7:08:34 PM
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C3 Starship
Posts: 4761
Joined: 7/25/2006
Status: online
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I have some Carter AFBs, and have always had good preformance.
Ya, ya gotta "kit" them once in a while, but you have to do the others too. 
< Message edited by C3 Starship -- 7/30/2007 5:35:29 PM >
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1980 L-82 Fastback (forward too)
Mono composite front and rear.
Full adjust ride height and
response.
400+ hp, 454, M-22, 3.07
http://i121.photobucket.com/albums/o225/C3Starship/Patch.jpg
2007 H. D. Sportster, XL 883 EFI
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RE: QJet Adjustment Help - 7/30/2007 7:02:18 AM
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Texas Jim
Posts: 445
Joined: 12/15/2005
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Yes, the AFV is the older version of the AFB and the same basic set up. The AFV I had was the manual choke model and I'm not sure that they came with an automatic one. And I agree that they do perform well and easy to work on. For a long time, 12 years back and more, I used the Carter carb (750s mostly) and a Torker II or Victor Jr. on all the small block Chevys (and others) I built. That combo was just a favorite of mine for awhile. They (Carter carbs) ran good, were reliable and required little maintenance. I'll run a "Demon" on the next performance engine I build.
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RE: QJet Adjustment Help - 7/30/2007 12:10:37 PM
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busnut
Posts: 123
Joined: 12/24/2006
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If you are idling at 900 then your main throttle plates are not closed and they need to be right closed to put the carb into its idle circuit. You need to turn the idle down and make sure the throttle plates are fully closed then you can adjust the mixture screws.If it is not in the idle circuit then turning the mixture screws will do nothing. Are you using a vacum guage to set the mixture or a tach?
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Owen ---- nothing like a big block and a car built to drive
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RE: QJet Adjustment Help - 7/30/2007 9:43:36 PM
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Texas Jim
Posts: 445
Joined: 12/15/2005
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Has this guy done anything with the carb yet? I suppose he may want to go through all the basic tune-up procedures including the carb. You're right, 900rpm is way too high for idling. And it very well may be that he's not using the "idle circuit." Some things are easy, and some things are tough unless you're "there" with afew tools to try a couple of things.
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RE: QJet Adjustment Help (update) - 7/31/2007 12:22:19 AM
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L82Steve
Posts: 11
Joined: 7/18/2007
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Sorry I haven't given an update sooner but I haven't had time work on it , anyway I finally pulled the carb, took it apart and found that the power piston was stuck open. The bowl had a layer of varnish covering the entire bottom about 1/16 thick and the jets were filled with gunk it was in bad shape, I'm surprise it even ran. I bought a rebuild kit, a book and did a lot of research before I tore into it and finally completed the rebuild about an hour ago. Everything went smoothly and I am looking forward to getting it back on the motor to see if my first ever rebuild was worth it. I appreciate all the great advice I will keep you posted on my progress and I'll try to get back to the forum sooner this time.
L82 Steve
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RE: QJet Adjustment Help (update) - 8/1/2007 4:25:48 AM
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Texas Jim
Posts: 445
Joined: 12/15/2005
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Really glad to hear that the rebuild went smooth. My first rebuild was a one bbl. from my '65 Volkswagen bug in high school. You jumped in with both feet taking on the quadrajet your first go- round. And I see more than one person was right.
Let me tell you a good one; I've had my 'Vette for about 3 years now, bought it "all of a sudden" never having planned on buying it. It's never driven far, is all original and is a beautiful looking car. But this car needs to be gone through; ie: the suspension. Well, the carb on my 'Vette still has the caps on the mixture screws. The carb has never been gone through. LOL It runs well, idles very smooth at 600 rpm and the accel. pump is working. LOL Do you think it's time?
Anyway, I am very glad that things turned out well and the best of luck getting it back on. The hard part is over and nothing but fun now as I'm sure it'll start up easy for you and run well.
I find with anything, that fear comes from "not knowing" and with a good manual and this site, all is possible for our 'Vettes. Thanks for the up-date.
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RE: QJet Adjustment Help (update) - 8/1/2007 10:21:49 PM
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L82Steve
Posts: 11
Joined: 7/18/2007
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I installed the carb today and thank god I labled all the hoses so I knew right where they went. It took a little to get it pumping gas to the carb but once it got up there it ran pretty good. I checked the timing again and adjusted the air fuel screws and they actually killed the car when I turned them all the way in so I know I did something right on the rebuild. I don't have a vacuum gage so I tuned them by ear. I just went on a 20 minute test drive and it ran great, smoother then it ever has. One question, I checked the sticker under the hood and it says that the idle should be set at 900 in park and 750 in gear. If I set the idle at 750 or lower in park it won't stay running when I put it in gear, does that sound right? Another thing I noticed is that the headlights come up faster since I timed and rebuilt the carb. How do I adjust the air fuel screws with a vacuum gauge?
Hey Jim, on your vette if it isn't broke don't fix it. I didn't have choice this time it was either fix it or don't ever drive it and I love driving it too much to let it sit. I just want everyone to know that I'am very thankful that there are so many people willing to help. Thanks to everyone who responded.
L82Steve
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RE: QJet Adjustment Help (update) - 8/4/2007 4:39:12 AM
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Texas Jim
Posts: 445
Joined: 12/15/2005
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L82, I have to say that you jumped in with both feet taking on the quadrajet for your first carb rebuild. My first was a one bbl. on my '65 VW bug when I was in high school, that I eventually replaced with a two bbl. along with a dual point Mallory distributor. A screamin' 1600 motor and a "super beetle" crusher. LOL
I don't know if the engine should die at that high of an rpm when you run the idle down. (although it doesn't sound right to me.) That darn ECM controls the carb in alot of ways which is honestly something that I'm not totally up on. My engine stays running after backing the idle screw out to the point of being in-op, but that may very well be due to the mixture screws being so far out from never removing the caps to adjust them. (one of the reasons for me needing to rebuild my carb.) With an all-mechanical carb, I have not a bit of trouble, but with that ECM helping out, I have to go back to the GM shop manual to read and re-read different parts. The head lights being faster since the rebuild tells me that you fixed a vacuum leak in the process. Either that or the resetting of the timing bringing up the idle and inturn the vacuum level. Sometimes the leak occurs at the base of the carb due to the bolts coming loose over time from vibration. All in all, it sounds like your rebuild was a success. Thanks so much for the up-date. And again, a heck of a 1st. time rebuild!!!
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RE: QJet Adjustment Help (update) - 8/16/2007 7:33:25 PM
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73shark
Posts: 1097
Joined: 4/18/2006
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quote:
ORIGINAL: L82Steve
If I set the idle at 750 or lower in park it won't stay running when I put it in gear, does that sound right? Another thing I noticed is that the headlights come up faster since I timed and rebuilt the carb. How do I adjust the air fuel screws with a vacuum gauge?
L82Steve
You might get away with 800-850 rpm in Park but probably no lower.
With the vacuum gauge connected to a manifold source (not a ported source), set the idle speed and then adjust the idle mixture screws for max vacuum. Will probably need to reset the idle speed while you do this. Also want to do in Drive for best results. Also make sure timing is correct before you start.
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So many toys, so little time
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