Those flaps are the choke plates, when cold they should be JUST about closed , NOT completely closed. If they are completely closed, no air gets into the carb The part on the side of the carb that has the 2 cooling lines going to it is the choke housing that contains a bimetallic spring that when cold, keeps the chokes closed to help with starting ( can give a lot more explanation but that is enough for here and now ) As the coolant gets warmer, the choke housing spring starts to loosen up and takes the tension off the choke flaps, allowing the choke flaps to open and be fully open when the car is warmed up. There is also a mechanism attached to the choke housing that will give the car a " fast idle " Again as the car warms up, this fast idle slowly comes off until it is back at where ever the normal idle is set up at. Sometimes , after warming up a bit, you have to blip the throttle to get it to come off the fast idle SO, your high idle may be related to this. Fast idle is usually set at around 1400 to 1500 rpm Sometimes if you " kick ' the throttle too soon, the idle will drop off too soon and it may stumble or die off. That same choke housing can be loosened off and you can rotate that housing to put more or less tension on the bimetallic spring which in turn makes the fast idle stay on longer or less. I get rid of all the emission stuff because where we are, they testing ended a few years ago ( thank god ) here. I block all vacuum ports except for a ported vacuum that I run to the distributor on the advance side, don't use the retard side at all You can run a line to the small outlet on the aircleaner as it was a way of sucking the gases coming from the valve cover breather back into the intake to keep things cleaner up to you,
The high idle maybe because it is on the fast idle circuit. Of course most of this does not come into play if you have a cable that you manually close the chokes and sets the fast idle ( it doesn't look like it here ) so how fast is the idle when starting the car? You also may have the distributor too far advanced at the moment. Start it up with the dist loose enough that it can turn but not sloppy so it will move on it;s own. You can get the idle down by turning the dist just until you can get the car to idle, then adjust to the timing marks.
First and foremost make sure that the point gap is correct as it has a direct function on timing( or set it with a dwell meter 38-41 degrees, set at lower number so when the little rubbing block on the points slowly wears down, the dwell will stay within the required specs ) Once this is all done, set the timing with a timing light Let the car warm up and make sure the fast idle and chokes are off ( choke plates fully open ) then you can adjust the carbs. Pretty easy on the webers, disconnect the linkage connection at the carbs so they work independently . You adjust webers for best smooth idle, so you screw the idle mixture screw in or out as needed to give you the best smooth idle Make sure that the idle set screws are not adjusted too far in causing a higher speed. I think that may be enough for now for you to get your head wrapped around this
Thanks, Rick