Hy 1949chevrolettruck, carbs are vented to the atmosphere, so the fuel can evaporate over time. Your carb probably has little or no fuel in it when you try to start the engine after a week. If your carb has an automatic choke then one pump of the throttle pedal will set that, and one more pump may squirt whatever is left in the accelerator pump well, if anything, into the manifold. That should give you the best chance of starting, but I think you may have to continue your practise of "priming" if it is a week between starts, hope that helps.
