Classic/Antique Car Repair: 53 bel air, good luck jack, chevy car

Question
why does my car not start everytime without priming the carb. 6 volt system 235 motor single barrel carb.

Answer
I don't know anything about your bel air.  I am a Model A guy, but here is what I think.  It has to be the carb.  If you can't get it rebuilt, or rebuild it yourself, at least clean is good and make sure the automatic choke is working.  Clean the plugs and check the compression.  Both of those things can keep it from starting good.  Stay with it until it fires right off everytime as it should.  The six volt system is all you need.  If you change it to 12 volts, that is just a Band Aid.  Keep the 6 volts.  I assume the fuel pump is OK.  Find yourself a chevy car club and join it.  They will be able to help you a lot.  
Good luck
jack