OK, I own both a cleveland and a edelbrock carb but not the avs series. ON mine, by the throttle plate is a screw with a spring. Its thr opposite direction of the idle screw. Meaning you adjust the idle screw standing in front of the truck and the kickdown screw is adjusted as if you were standing at the back of the truck. Which is not possible so you stand on the drivers side of course. If you turn the screw in it will allow the throttle bracket to it it earlier and open the secondaries sooner. Let it out for it to open later.
Keys:
screw is on drivers side
has a spring for tension
on throttle bracket assembly
screwed in for sooner opening
best of luck!