Your problem is most likely caused by the gasoline blends sold today. Modern fuel is much more volatile than real fuel from 60 years ago. It isn't even the same fuel that we had 20 years ago. Being more volatile, it evaporates much more rapidly and at lower temperatures than it did in the past.
My Toronado's Q-Jet evaporates most of the fuel in the bowl in an hour or so after parked hot. I've seen others on this site say that their AD truck fuel bowls will evaporate in 30 minutes after parking.
I drive my truck every day or every couple days. If it's 3 or more days I have to crank longer and pump to get it started. If it's a day later it's a little easier.
Carburetors are open to the atmosphere and will evaporate the fuel if not refreshed regularly.
