Classic/Antique Car Repair: 1964 1/2 Mustang, ground cable, new paint

Question
My 1964 1/2 Mustang runs great when you first start out with it, however once you run it for 30 minutes or so it starts missing and then if you turn it off it won't start unless you jump it.  It acts like the battery is dead, just clicking when you try to start it after you have run it for a while.  The body and interior are completely restored to the original specs.  No changes have been make to the motor etc.  It is a three speed manual with a 170 ci motor.

Answer
Aurelia, make sure that there is a bonding strap (ground cable) between the body and the engine. This was usually attached to one of the back valve cover bolts on most of these cars and ran back to the fire wall. That completes a good ground between the body and the engine of the car. The voltage regulator on these cars is attached to the body and unless there is a good ground between the engine and the body the charging system will not keep the battery charged. It could be that the new paint on the fire wall is preventing that ground wire from making a good contact if the wire is present. Good luck.
Brad