Carb Problem on GM 350
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New User
Joined: Jan 2005
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From: College Station, TX
Carb Problem on GM 350
I have a 1974 Oldsmobile delta 88 with a GM 350, when started the engine immediately goes up to around 5-6000 RPM's. It's got a relitavely new 4 barrel carb on it. Best thing I can think of is maybe the idle screw may be way off. as far as I can tell the accelerator cable isn't sticking. Any one have any insight as to what may be the problem?
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From: College Station, TX
Originally Posted by Drover
What type carb? Make sure the throttle return spring is hooked up.
Lead Driver
Joined: Feb 2003
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From: Oak Harbor, OH
It sounds like the choke is WAAAAAAAAAAAAAAY out of adjustment and the high idle is set way too high as well. On the LEFT side of the carb (as you look at it from the front of the car) there is a big plastic thing with a wire going to it. That is the choke. Look down towards the bottom of the carb. It's kind of hidden. Start the car and turn that screw down.
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From: College Station, TX
Originally Posted by pfogle
It sounds like the choke is WAAAAAAAAAAAAAAY out of adjustment and the high idle is set way too high as well. On the LEFT side of the carb (as you look at it from the front of the car) there is a big plastic thing with a wire going to it. That is the choke. Look down towards the bottom of the carb. It's kind of hidden. Start the car and turn that screw down.
Senior User
Joined: Oct 2004
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From: Colorado
The choke pull off on a q-jet isnt capable of making it rev to 6K if thats an accurate RPM reading. Check the throttle linkage and make sure it's returning to the rest/idle posistion, pop the choke flap open and check the throttle blades to make sure they are closed, pop the secondary flap (if eqquipt) and make sure those throttle blades are closed. Theres linkage right behind the choke well not behind the choke but between the choke and carb body that is similiar to any other carb, pull the throttle open slightly and push this down. This will kick the carb off high idle and let you know if the fast idle is the problem. If everything checks out you have a huge vacuum leak thats allowing the carb to suck enough air with the choke closed to allow it to hit 6k.
Lead Driver
Joined: Feb 2003
Posts: 8,140
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From: Oak Harbor, OH
It's not the pull off I'm worried about. There are 2 idle speed adjusments, one for normal idle and one for high idle. If the car is cold the choke will close, and in turn raise the idle to compensate. Then when the choke warms up it pulls off completely bypassing the high idle circuit, and running a normal idle. If the carb was setup improperly from the box the high idle could be way out of spec.
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