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73-87 Chevy _ GMC Trucks => Fuel Systems and Drivability => Topic started by: 1979C20 on March 09, 2011, 02:28:39 am
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I replaced my distributor a bit ago, and finally properly set my timing a couple days ago. When I set my timing and idle, it was done at operating temp, vac advance pulled and plugged and I leaned my airfuel mixture a bit, because it was rich. After set, while driving, when I come to a stop my idle is high. If I lift my pedal with my foot it will lower to where I set it. I looked at my throttle linkage on the carb and after letting the gas out, the throttle doesnt come back and rest on the idle screw anymore. When I lift the pedal it rotates the throttle backwards and makes the idle set screw rest on the linkage how it should. Any recommendations on a fix?
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Throttle return spring from linkage on carb. to cable bracket. Tighten it up somehow or get a new one.
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Also make sure that the cable isn't kinked or binding in the sleeve.
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Good point, Grim. It could just be the cable sticking and needing lube, don't know if that's what you meant by "binding in the sleeve."
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Yep, that's what I meant. Also my old q-jet would bind like that because of bad throttle bushings.
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This is a qjet, how do I check throttle bushings? I put new return springs on it and ive already lubed the cable.
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With it idling, keep the throttle rod turned closed, but grab the end of it where the throttle cable and return spring hook up and push/pull it towards the front and back of the truck and straight up and down to see how much slop is in it. If you can hear whistling when you move it, or it changes idle speed, it's sucking air (vacuum leak) and if there is alot of slop in it sometimes it can catch and bind and not let the throttle valve rod turn to bring it back down to normal idle.