Evaporating Fuel in Carter 4-Barrel Carb?

Hi

I face the following issue on my 4-barrel carb 4120s on my 1966 Barracuda (4-speed manual):

Leaving the car standing for several days, I always have to turn the starter for a long time until there is enough gas to fire the engine. I do have enough fuel coming into the carb at first pedal already. Once started it runs perfectly.

Question: Is there a possibility, that these carter carbs have a small hole or channel somewhere, that favors evaporating the fuel in the float chamber?

I am soon going to switch the carb for the right no. 4119s

Thanks, Robert