Tips for tuning dual Carbs?

I have used the uni-syn to adjust dual 2 barrels on a 4 cylinder bug motor. You first want to get all the idle stops set the same. That can be done by going equal amount on throttle stop screw from fully closed. Then make sure the linkages are corrrect such that all return to stops at the same time and open fully at WOT. All this assumes the the throttle plates are correctly aligned on each carb. The best way for me to do that is look how light leaks around the bore, throttle closed.

On the Dellortor carbs there is an air volume screw that controls air bypass of the throttle. Use uni-syn and tweek those to give equal readings on each bore. In your case slight tweeks to idle speed, then re-tweek linkages..... repeat till all is well.