I am going to run dual 4 bbls on my v8. I am going to use 2 Holley series 4000 carbs (like used on T-Birds). I was made aware of there being some sort of balance tube that needs to be run between the two carbs to balance the secondary openings. Can anyone describe this to me or perhaps show a picture of this application? Or, direct me to somewhere that I might see something like this?

The application is a large displacement Ford Flathead V8. Both carbs will be directly linked (not progressive), with one carb facing it's normal direction, and the other reversed. 

Thanks for any and all assistance.

Jim