Rochester Quadrajet issue

[83c10_Owner]

I have a Rochester Quadrajet carb 17083224 on a 83 c10 Silverado with a 305 engine. Also everything is stock. My question is, trying to adjust the carbs fast idle and it effects the curb idle. Well I try to fix the curb idle and the fast idle is affected also the next morning. I’m still learning on the carb so is it a vacuum issue or something else. It acts that way during cold or cooler weather not in warmer weather.

 

[fast 99]

When choke is completely warmed fast idle on right side shouldn't change idle speed. Either choke isn't warmed enough [no preheat], bad choke thermostat [check for open circuit ohm it] linkage is stuck and/or not adjusted correctly. Try pushing down on the fast idle cam with a finger. Needs 12v power on electrical lead at choke thermostat. There are several other adjustments that will effect cold operation but this is where you should start.

 

[ButchM]

I have a Rochester Quadrajet carb 17083224 on a 83 c10 Silverado with a 305 engine. Also everything is stock. My question is, trying to adjust the carbs fast idle and it effects the curb idle. Well I try to fix the curb idle and the fast idle is affected also the next morning. I’m still learning on the carb so is it a vacuum issue or something else. It acts that way during cold or cooler weather not in warmer weather.

Dan
Set curb idle with engine fully warmed up, it should not need adjusted after that, leave it alone.
The fast idle settings are for a cold engine when the choke is in operation. If they are amiss the problem is likely in the choke linkage of choke pull-off.