Engine Hard Starting After Days Of Rest

1967 440 Magnum, 600cfm Carter carburetor, electronic ignition, manual fuel pump. Engine was just tuned up with all new filters, wires, plugs, rotor, etc. Runs great once started. Battery good.

The next day after a drive, the engine starts right up with one pump of the gas pedal. Same with day two. Day three, takes a little more cranks of the starter. After that, I might have to start the engine a second time to get it going. A week later, can be much more difficult to start.

Is hard starting caused by evaporation of gas in the carburetor? Does anyone else have this issue and have some tips? More pumps of the gas pedal?