I started playing with the carburetor on my 1979 Pontiac Catalina again today to see if I can figure out what's causing the constant fast idle. I rigged up a temporary heat riser tube with some heavy vacuum hose, so the choke is now getting hot air. If I manually manipulate the metal piece with the E embossed in it and turn it to the right, it will lock in place, fully open the choke plate, and disengage the fast idle. All the motion seems smooth, with no binding. It will stay this way, but if I touch the throttle at all, it immediately snaps back onto the fast idle, even when it's hot. What would be causing this? The vacuum choke pull-off works, but the linkage between the choke and the pull-off doesn't go all the way to the end of the slot in the pull-off arm when it opens itself up. I attached some pictures to make it clear what I'm talking about. I assume it's supposed to?
Should I run the engine until it's hot, then adjust the tension on the choke until the linkage is all the way to the right?
Definitely try that to make sure you got it open when it's hot but it might be wearing out internally you need a new carburetor. If it is repairable what you want is an ice cold engine open it up loosen the choke and then adjusted so the clothes choke is fully open then turn a slightly into it just barely closes the choke and then set it there
