No load no opening normal
You must have a load on the engine at WOT like on a dyno to get the blades on the secondary to open. If you are free revving that engine to see this, you will NOT get the secondaries to open at all. The engine air demand has to be great enough to open them under full load and higher rpms than maybe 4000. You can not make a real mechanical double pumper very easily out of a vac secondary. We used to put a bolt in the linkage to make it open the secondaries about a 1/4" to quicken the opening of them. However a bog will likely follow. Sounds great with the air cleaner flipped! Everything Mark said as well in the earlier entry.
Bruce