It is a 4 corner, it is a 650 cfm Speed Demon. Everything I see (and talking with Holley tech support today) they say the secondary idle slots should be invisible from the bottom. I'll probably just have to try it.
Have blades in the secondary been messed with that you can tell? You may be able to loosen them on the shaft and see if they close up more of the venturie. And make sure the venturie is clean so they can close all the way.
If you get your timing squared away it will help get your idle figured out.