Recently rebuilt motor was running fine. I was cleaning up the motor and noticed a vacuum leak slowed motor when I directed water to back of carburetor. Fixed leaks and ran fine. The next day the alternator started overcharging so I replaced the alternator; ran fine. I listened to the radio with the key in on position while waiting; tried to start, nothing. Coil was very hot so I replaced coil, nothing, replaced distributor (these were under warranty) and car ran for twenty minutes then quit. While trying to find problem it started briefly and quit. It appears to be no spark. Can you help?