Quadrajet issue
07-24-2016, 08:22 AM
#1
Safety Car
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Quadrajet issue
The fast idle works when I first start the car cold, but after it comes off it at 180 deg., idles very low (almost dies). Then after driving for a while, 15 miles or so, starts idling a little fast (900-950 rpm). What could be wrong?
07-24-2016, 09:22 AM
#3
Le Mans Master
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Fast idle cam is not operating properly. You need longer duration on the "fast" step of the cam. The motor drops off the fast setting too early (before the engine warms completely) and then when the engine is at operating temperature, it idle too high because someone has set the idle speed too high to compensate for the incorrect fast idle cam setting.
07-24-2016, 02:59 PM
#6
Burning Brakes
07-24-2016, 03:06 PM
#8
Safety Car
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Location: Arlington TX
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2023 Restomod of the Year Finalist
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Fast idle cam is not operating properly. You need longer duration on the "fast" step of the cam. The motor drops off the fast setting too early (before the engine warms completely) and then when the engine is at operating temperature, it idle too high because someone has set the idle speed too high to compensate for the incorrect fast idle cam setting.
07-25-2016, 12:19 PM
#10
Team Owner
Hot air choke, or 'divorced' choke? If divorced choke (this is the normal '69 design with can/coil on manifold), just bend the choke rod so that coil winds a bit tighter...then it will take longer for heat to turn choke completely off.
The Chevrolet Chassis Service Manual for 1969 cars will have all the detail about making carb & choke adjustments in the Fuel System section of the manual.
The Chevrolet Chassis Service Manual for 1969 cars will have all the detail about making carb & choke adjustments in the Fuel System section of the manual.
Last edited by 7T1vette; 07-25-2016 at 12:19 PM.