A lot of holleys in general are fat from what I`ve seen and my car runs cleaner and faster w/28 squirters and jetted/set up leaner on the idle and cruise circuit. If you can`t read plugs a wide band is your friend. Years ago Cab told me this; there`s 3-circuits on a carb(2-circuit) idle, cruise and wot so we`d set up the idle circuit first and read the plug idle only then make necessary changes. Then we`d work on the cruise circuit driving on primaries only and read the plugs then finally wot. Took a lot of work but w/out a wide band I don`t see any other way and although it`s not perfect, it`s a great reference tool and now my plugs look like the wide band indicated. Slightly rich at idle and cruise and nice at wot..........