when I put my engine on the dyno, my builder started with the center carb only to break it in. He has block off plates for the outboard carbs. Tuned in the center, then added the outboards after is ran fine. I can't help in any other way since my car isn't finished and running yet. My carbs were rebuilt by a local carb guy, and they were spot on with the jetting. I tried going larger, but lost power. Went back to where it was set when I got them. Bummer this is difficult. Might just be easier to get a set of new carbs from Holley and sell your old ones.??