| If you are parked in the driveway or garage with the hood open and open the throttle while watching the secondaries, you won't see the secondaries open. They don't open that quickly, because you need to sustain flow through the primaries in order to create enough of a vacuum signal to start opening the secondaries, and sustain it to get them to open completely. Try that with no load on the engine and you're going to be sending rods through the block wall before the secondaries start to open.
A "bog" at 3000 RPMs regardless of throttle opening is not a secondary, or even a carb problem. It's an ignition problem (most likely). Could be other things, though, but still, not a carb problem. | 
