warm start

ok when i start my truck cold it usually cranks right over no problem, but after i drive it for about 30 mins or more, and then stop and turn it off and leave it for a minute it wont turn right over i have to turn the key a bit and then press the accel pedal to get it on. what might this all be about?

My guess it's heat soak. The fuel in carb expands and runs theough the venturi into the intake manifold flooding the motor. I have had the same issues durring hot weather. Modern gasoline has a lower vaporization point than what these cars were designed for and causes a lot of heat soak as well as vaporlock issues. The fuel manufacturers get away with this since fuel injected engines aren't affected by these problems.
I have done a few things that have helped a lot but havn't totally fixed it:
1) Lowered the float level by 1/16"-1/8" below specs.
2) Blocked the exhaust heat riser ports to the intake manifold.
3) Installed a Cagle fuel pressure regulator ahead of the carb.
My next change would be to install some sort of capacitive discharge system (like MSD) to the ignition in order to help start the flooded motor. I have a Duraspark system now but the CD system might be worth trying.