Hey TKM, I jumped on tonight to do some research on a very similar issue I am having with my 1951 3100 Chevy with a 1957 235 truck engine. A couple weeks ago, after driving the truck for 1 hour, the engine cut out completely while still driving. When we popped the hood, there was fuel leaking out from the carb and the engine would not turn over. In my two years of ownership of this truck, it has never behaved like this. Today, we changed the spark plugs. The old ones were black and sooty. The engine fired up for 15 seconds, and abruptly died. There was still fuel coming out from the carb.
My next step is to replace the ignition coil. After reading this thread, I am also going to check the carb again for debris or a stuck float. The third plan of attack (if the first two don't work) is to look at the distributor more closely. Please let us all know how you fair with the new coil. Best of luck!
Fix the carb problem first before you spend money on ignition parts. Black and sooty plugs means they're getting too much fuel.
