Idle Too High

67Dart273 said
Retarding the timing is NOT the answer, even though it will lower the idle speed

Finding the REAL problem is the answer

Is this a new carb, or did you buy it used? Some guys "with big cams" used to drill holes in the throttle plates to try and help a big cam idle better --get the butterflies back down into the transfer slots

Either you have something hanging up -- like the butterflies can't close, or a vacuum leak.
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X2. Check the linkage that opens the secondarys if it's bent or binding, sometimes the throttle plates won't close all the way. You may want to pull the carb off so you can see if all the throttle plates close and there are no bent ones or extra holes drilled.