From: Mike Patterson
Email: [email protected]
Date: December 19, 2001
Idle adjustment is set on individual Carbs/engines. There is no such thing as a one size fits all (i.e. 1 turn, 2 turns etc) adjustment. The Idle screws are turned to get smoothest idle out of the engine. On a properly runnning and tuned engine, that is fully warmed up (drive it a few miles if necessary)do the following. Put the car in neutral, and make sure the choke is fully off. Set the idle speed (the adjustment on the carb linkage to a reasonable Idle (say around 750 rpm). Turning one idle adjustment screw at a time, first turn the screw in until the engine runs rough then back out until runs the smoothest. (If you keep turning out after that point you just waste gas and foul plugs). Do the same on the other idle screw, set the idle speed (the screw on the linkage again) and your done. A trick that was shown to me many years ago, is to pick a spot on the engine (usually a valve cover corner) and a spot on the fire wall and watch these as you as do your adjusting until you get the least amount of shake (thats should be about 2 snorts for you alumcan). If you can't get a decent Idle out of it check the basics, points (condition and dwell/gap), cap, rotor, wires and plugs. If one or both Idle screws can be turned all the way in without making any diffrence, it usually means you have a vacume leak somewhere, or the carb needs rebuilt due to plugged passages. (This can sometimes be remedied by taking the offending screw out completly and squirting a little carb cleaner through the hole.) If you still can't get a good Idle, it's time to pull the old compression guage out and start checking the major things out. Hope this helps.
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