The condition commonly referred to as BOG by just about everyone is caused by a quick loss of vacuum that results in too much air with no velocity. Until there is enough air velocity through the secondary boosters to draw fuel you have the bog. Given the same size carb a smaller engine will be quicker to bog because the smaller displacement cannot pump air as fast as a larger engine can.
This is one of the reasons Holley developed the double pumper carbs that have an accelerator pump for the secondaries. The shot from the secondary pump adds fuel to keep the mixture from being too lean until fuel is drawn through the secondary booster nozzles by vacuum / velocity when the secondaries are slammed open.
The vacuum diaphragm that Holley uses and the air valve that Edelbrock uses do essentially the same thing in holding back secondary action until air flow velocity is near correct. It probably isn't wise for the average person to attempt modifying the air valve in an Edelbrock Performer nor have I ever found it necessary on a street carb that has been set up correctly. Correcting it is not as easy as changing the secondary vacuum spring on a Holley.
The new AVS Edlebrock has a secondary valve like the old Carters adjustment and makes fine tuning the secondary opening much easier.
