<VV> Special Secondary Carbs??

[Grant Young]

I am hoping someone has some personal experience using the factory modified secondary 140 HP carburetors
that have an idle circuit. These are the later model ones that have a primary venturi cluster and idle discharge
circuit and hole in the base, but are otherwise non-adjustable. They were supposedly supplied to dealers to help with 
customer complaints. I'm not sure if they came with the cars (but would like to). I have several pairs on hand.
I think they might be more rare than A.I.R. carbs with enrichment circuits. I would like to know if they really worked?
Thanks,
The Carbmeister