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73-87 Chevy _ GMC Trucks => Fuel Systems and Drivability => Topic started by: kj4ltc on November 18, 2018, 09:50:07 PM
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Not sure where my issue is with the choke on my carb (1983 k10 305) I have some cracked vac lines from the carb and some cut and capped at the canister. How can I test and isolate choke components? Thanks in advance, if there’s any more info y’all need just ask.
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Is it a hot air choke or an electric?
Bruce
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Sorry for the delay, I wasn’t sure right off hand. It is electric choke, but it appears that the choke linkage is bent or broken or both, I also have several vac lines on and around the carb that are broken and/or missing....I probably need to get some it cleaned up and take some pics
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I tried to get some pics tonight, lighting is very poor....I’ll try again later
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Update, I have more issues than just the choke. I haven’t had much time to mess with this truck, but I have no linkage at all to the butterflies on the secondaries, no spring tension at all on the choke, not getting any high idle. Oh, and a fuel leak where the filter is. Who is a reputable source for quadrajet parts....and what modle do I have 1983 k10 305
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Pics would really help... look for an aluminum tag with numbers on it. Unless it's lying somewhere with your butterfly linkage. ???
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I may have more trouble than I know how to handle, I’ve searched for a model number all over this thing. Choke does not function correctly, high idle does not engage, butterflies for the secondaries have no linkage, and the truck will not idle. I feel confident that I could rebuild this carb but until I can find the model number I can’t even find where to begin with this 😡😡
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Search 'Quadrajet numbers on this site, I think it's going to be helpful
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I know this is old, but I hear a lot of people speak of having trouble finding the number on a Q-jet. If there isn't a tag on the body (which was an old way of doing it in the 1960s and early 70s, before most of the squares were built), then the number is on the body of the carb on the outside of the driver's side secondary venturi below an airhorn screw. It is stamped vertically on a flat vertical surface near the throttle linkage and will start with 704, 1705, or 1708, followed by 4 more digits. Most important to remember, the number will probably be impossible to read unless you clean that surface with something (spit on your finger and see if you can bring out some numbers).
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I've attached a picture of the original Quadrajet from my '75 GMC, and circled the part number (7045583). Newer Quadrajets will have a longer parts number and the first digit will be a 1 (like 17080213).
Getting the choke to work exactly right on a Quadrajet can be a real PIA. If you look at the GM repair manual there are at least 4 measurements and linkage adjustments that affect the choke. Its also possible that your truck was converted from hot air to electric choke, and someone may have not understood how to install the kit. There is also one or two choke pull-offs that are vacuum operated. One of them operates to pull the choke open slightly once the engine is running and you have vacuum.
When you said your secondaries don't work, are you just looking at the air flaps on the top of the carb? Those are the secondary air flaps, but the secondary butterflies are down underneath, and the butterflies are mechanical. The carburetor linkage will always begin to open up the secondary butterflies at a certain throttle position and they should be wide open at full throttle. However, the air flaps on top are just held by a light spring, and they will not open unless there is enough vacuum "pull" (or air flow into the engine) to cause them to open. You cannot make these top air flaps open by just moving the throttle linkage.
Bruce