As already mentioned, check carefully for vacuum leaks and/or hoses off. Make sure the throttle moves smoothly and the linkage does not rub or catch on anything. Put the air cleaner back on, and check again for any binding. A stock air cleaner may not seat correctly on an Edelbrock because the fuel fitting on the passenger side gets in the way. Use an air cleaner spacer, if necessary, or buy the Edelbrock dropped fitting.
Adjust the idle very low (500-600 rpm) and with the vacuum advance disconnected and vacuum line plugged, adjust base timing to about 12 degrees. Then rev it up to about 2500-3000 rpm and verify you get about 18-20 degrees more for mechanical. Go back to idle and connect the vacuum advance line to full vacuum, and verify it also gets you about 18-20 degrees advance. All this shows that your distributor is working.
Take the AVS2 off and adjust the idle stop screw so that with the choke off and linkage at normal idle, you get a square transfer slot exposure. This will get you the best adjustability for mixture and off idle transition.
Warm up the engine and ensure the choke is fully off and it is at curb idle. Now gently turn the mixture screws in, and turn them back out the number of turns Edelbrock recommends. Then connect a tach or a vacuum gauge, and adjust the idle mixture for the best rpm. It should not take a lot of adjustment for a stock engine.
