Carburetor help

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73Blazer

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I'll start by saying that I have a LOT to learn about working on old trucks. Or anything really. I just traded for a 2wd 74 Cheyenne Super. The night I got it, it ran absolutely perfect. Imagine that. Started it up a couple of days later and headed to work, I got about two blocks away and it started feeling like the gas was cutting out intermittently. It felt like it wasn't getting a constant flow. Got it home to look at the carb and realized I know NOTHING about it. It is stuck in the open position. I noticed the rear passenger side bolt was missing. Maybe missing a small hose and something electrical on the driver side. Posting pictures in hopes that someone can point out anything blatantly obvious. Any help would be greatly appreciated. Thanks in advance
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1987 GMC Jimmy

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Here's what I see. Your dashpot/idle stop solenoid is unplugged for some reason. There should be a little single wire connector that plugs into that prong. What that does is whenever you turn the A/C on, that bolt head nudges against the throttle arm to compensate for compressor load whenever it's idling. It is adjustable, by the way. I can't get a good look, but something doesn't look right with the choke pulloff tube. That should be going into the carb not somewhere else. The retainer clip for the detent cable is missing so you need one of those so it doesn't fall off. Your EGR valve is unplugged for some reason. Not a big deal, but I thought I'd mention it. I'm assuming that the valve got stuck open or couldn't hold vacuum, and it caused it to run poorly so they just unplugged it and sorta plugged the port. I see some half ass plugging of the vacuum ports and what looks like gray RTV around part of the edge, but I could be wrong on that. If so, that's not good. The carb should only have two bolts, though. What I'd do is just pull the carb, get a set of vacuum caps, get a new base gasket for a Rochester 2GV, and get a new fuel filter. You need to correctly plug the ports that were plugged with bolts, reconnect the pulloff tube to the carb, undo that flare fitting and big nut to get to the filter and replace it, make sure the intake is perfectly clean before you reinstall (if you have to scrape, do so very gently and wipe clean with a solvent such as carb cleaner - do the same for the base of the carb but don't scrape at it), and bolt it down snug in a diagonal pattern. Don't over tighten it. I would like to know what emissions components have been deleted, and where the remaining vacuum lines go to from the carb. What did you mean when you said it stays open? Are you saying the choke is open when it's cold? If so, I'll attach a video that shows how to adjust the choke and fast idle on a 2GV. I wish I could help more. I know some about these carbs only because they're Rochesters, but I know plenty more about Quadrajets. If it doesn't work out for you, I'd swap intakes, throw a nice remanufactured Q-Jet on there, and be done with it.

Here's what a properly connected choke pulloff looks like. And that video was for a 2GC. Let me see if I can find something appropriate.

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Better let someone who's familiar with these supplement on the adjustment parameters. Another issue could possibly be that thermostat that controls the choke.
 
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73Blazer

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First off, thanks for your detailed response. I'll try to respond to all of it that I can. I didn't know what the dash pot idle thing was until you explained it but i knew something was supposed to be there. I wonder if it was unplugged because I don't have a compressor for the AC? As for the pullout tube, i'll check that tomorrow and see if I can figure out where it goes/should go.... So I'm not actually missing that bolt? It's only mounted with two bolts, correct? I'm gonna pick up the vacuum caps and a filter tomorrow as well. I'll probably just do like you said and take it all out. The problem is that I'm having a lot of trouble finding a picture or video similar enough to compare it to, to see where all this stuff is actually supposed to go when I put it back. Also, I'm afraid if I put things back like they should be, I'll find the reason they boogered it up to the way it is now. Gotta start somewhere though.. I really do appreciate the response. I didn't know what much of it meant but was able to look it all up and learn a lot more than what I knew before. The quadrajet option is looking great right about now.
 

74 Shortbed

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That is called a "divorced choke" it is correct, rod is connected to a coil similar to electric choke except it uses heat from the manifold. Looks like a lot of emissions crap was removed an from the looks of it you probably have vacuum leaks, could be the pic but the fuel line looks like it has good size kink in it causing a restriction, probably could cut an inch or better off and straighten it out, the dashpot controls idle speed instead of just a screw, it screws into the lever and is how you adjust the idle, when you shut the engine off the plunger retracts and close the butterflies completely, purpose was to prevent overrun/dieseling after shut down on emissions equipped vehicles, they are a good item to use when a big cam is used and have to have a high idle..... But, as said above I would also recommend converting to a Q-Jet, way better performance and better fuel mileage..
 

gpmorgan

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Those 2 barrel carbs are very good carbs. There is one main concern with them though. They are prone to get loose where the carb bolts together. So while you have it off, check the screws that hold the carb together. You will see them from underneath the carb.
 

1987 GMC Jimmy

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First off, thanks for your detailed response. I'll try to respond to all of it that I can. I didn't know what the dash pot idle thing was until you explained it but i knew something was supposed to be there. I wonder if it was unplugged because I don't have a compressor for the AC? As for the pullout tube, i'll check that tomorrow and see if I can figure out where it goes/should go.... So I'm not actually missing that bolt? It's only mounted with two bolts, correct? I'm gonna pick up the vacuum caps and a filter tomorrow as well. I'll probably just do like you said and take it all out. The problem is that I'm having a lot of trouble finding a picture or video similar enough to compare it to, to see where all this stuff is actually supposed to go when I put it back. Also, I'm afraid if I put things back like they should be, I'll find the reason they boogered it up to the way it is now. Gotta start somewhere though.. I really do appreciate the response. I didn't know what much of it meant but was able to look it all up and learn a lot more than what I knew before. The quadrajet option is looking great right about now.
I don't know why the dashpot is unplugged. The Quadrajet version looks somewhat different than that one, but that's definitely what it looks like. Was it not equipped with A/C and the compressor's just missing? And yes, two bolts.
 

Mrisinge

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The "dashpot"/solenoid was used on these engines to prevent dieseling after the ignition is turned off. The idle speed is adjusted using the bolt in the solenoid when it is activated. It should be connected to a wire that is hot when the ignition key is in the on position. When you turn off the ignition, the solenoid retracts and the throttle blade closes completely. This is what prevents dieseling.
 

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