Most of your automatic chokes on V8's are set to run the fast idle @ 1500-1700 rpm, a tap on the gas pedal will bring it down to 1200 or so.
On any holley automatic choke you can adjust the fast idle by using a small flat blade screw driver OR a 1/4" wrench. This fast idle screw is in a terrible spot really... Have someone sit inside the vehicle with thier foot on the gas (full throttle and engine OFF) while you adjust the screw. Locate the choke housing on the right side of the carb, look towards the base of this housing near the throttle linkage. You'll see a lever with a bolt going through... this is the fast idle adjustment. Keep in mind, every 1/4 turn of the screw = roughly 200rpm.
Now set the choke on its highest setting, let off the gas and start the engine. Your fast idle should be 1500-1800 on the highest setting. Of course you can set it anywhere you like.
Sorry I dont have a pic, I'll see if I can round one up if anyone cant find what im describing
