Well said!!! :smiley_thPhil, just a little expansion on the technical explanation for the non-mechanically inclined, on what the vacuum hose to the petcock really does.
The middle vacuum hose does not suck gas into the carbs, but "sucks" or applies vacuum to a rubber diaphram which opens a valve and allows gas to flow by gravity through the two outer petcock hoses into the carb float chambers.
In other words, in a properly operating petcock no fuel passes through the vacuum hose.:smiley_th