My experiences with dozens of these carbs on a variety of engines is they are pretty much ok on the secondaries as they come out of the box unless you have an absurdly big carb on a smaller displacement engine. If you decide to increase the secondary jets to the maximum the engine can use it becomes part seat of the pants and part visual, neither of which is pin point accurate.
Install the jets and with the engine totally warmed up have someone follow you and watch for black smoke as you open the secondaries. When you reach the size jets that give you the smoke out the exhaust you need to drop back a size or more until the smoke clears. This is not super accurate but will give you good response and decent driveability when you mash open the secondaries. Follow their booklet carefully and have the primaries tuned correctly before you mess with the secondaries.
Don't be misled by all the so called carb experts who will tell you to remove the secondary air baffle plate. That is in there to prevent bog until the airflow is high enough to draw gas through the booster nozzles. It does the same job as the secondary vacuum diaphragm on a Holley except it is non adjustable and has nothing to wear out. It works so don't fix it!
Mike
