secondaries wont open

Holley says you really shouldn't feel the secondaries (vacuum) open, it should be a smooth transition.

This is from the Holley site:

"The secondaries will not open by free revving the engine. The engine needs to be under a load before they will open. If you are still uncertain if they are opening or not you can take a normal paperclip and clip it onto the secondary diaphragm rod. You will then push it up against the bottom of the secondary diaphragm housing, now you will need to go out and drive the vehicle. When you return you will be able to look at the position of the paper clip on the rod. If it is lower on the rod then you can tell the secondaries opened and how far they opened. This is useful in determining if you need a heavier or lighter secondary spring."

I'd also check to make sure the diaphragm isn't ripped or has a hole in it somewhere. Also make sure the o ring is in place to seal the cover. Another thing to check is that your throttle linkage isn't binding and that the cable is adjusted correctly to allow full throttle to be reached.