It's basically a precisely controlled vacuum leak, down each side of the carb. This allows the engine to get more air with less throttle angle.
The system, when used correctly keeps the main system off line at idle speed and eliminates any "nozzle drip".
It works well with big cammed/low vacuum at idle engines.
It does not make up for not having enough idle fuel available to the mixtures screws, so don't expect it to cure "nozzle drip" unless the carb is correctly set up for what it's being used on.....Cliff
