holley 1945 losing its prime

idk,..fuel stays a couple weeks in 100 degree weather, wont stay 3 days in 30 degree weather... dont think its a evaporation issue but ive been wrong before
That's good to know. Clamp off the fuel line at the carb or disconnect and plug at both ends. Let it set a few days to see if the fuel is disappearing from the carb through evaporation (or leak). Somehow you need to separate the components to see where it's going.