Carb issues...
July 10th, 2016, 7:55 PM
#1
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Carb issues...
Hey guys. I have a 77 Chevy 350 Silverado. I just rebuilt the carb. However I tore it apart 4 years ago and never bothered to label anything. I have found enough diagrams and such to put everything back together properly including all the correct vacuum line placements from the Internet... However. She is burning very rich. I have tinkered with my choke as well as my air/fuel screws on the front of the carb(2 of them) and still no avail. It's just runs rough no matter what I do. Oh yeah it is a Rochester quadrajet 4 barrel carb. Any insight is most appreciated!
Josh
Josh
July 10th, 2016, 8:15 PM
#2
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Runs rich - at idle or while driving too? The two screws should be your idle mix and will not affect running off idle. Is choke plate fully opening as it warms up? My 1st guess would be floats not adjusted correctly. I assume fresh gas in use?
July 10th, 2016, 8:27 PM
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It only runs rough during idle. From a complete stop when I apply a little gas it wants to die out before the truck will begin moving. Choke plate was originally wide open and was running great. Just a little rich. I watched a video this morning about setting your choke. So I set my choke to about a 1/4" open before warm up. Truck has ran like crap ever since. Yes, fresh premium gas in use.
July 10th, 2016, 8:36 PM
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I tried to set my choke back how it was before (wide open essentially) and it kind of started running leaner. However after taking it for a drive I noticed when I put it to the floor I have nowhere near the power I had before. Almost like all 4 barrels aren't opening now.
July 10th, 2016, 8:57 PM
#5
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Does the choke open up as the motor warms up? I have a rochester on my 68 elcamino. If I remember, with a warmed up motor, you close idle screws slowly till rpms drop, then open back 1/4-1/2 turn. That's your idle mixture setting. When you say it wants to die at take off, sounds like accelerator pump out of adjustment. You should see a squirt of fuel down the carb throat when you pump the throttle.
July 11th, 2016, 6:25 AM
#6
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Are there any numbers stamped on the carb body. Check them to make sure the carb is from a 77 350 Silverado. I have run into this previously when a previous owner put a different carb from another year on and that would make the adjustments different. Also it could require a different rebuild kit. This is just a possibility.