One and done electrical issue. (won't start)
 

I have a 67 SS 396. I don't drive it often. I was driving around the other day. I got the car back in the driveway and shut it down. When I tried to restart it a second later to move out of my wife's way the starter churned for a split second and that was it. All the electrical shut down. Turn the key back and nothing no lights, no radio, no "gen" light. nothing. Disconnected the battery and reconnected and the electric comes back until you engage the starter. Then all electrical is dead again. The battery reads 12.7v. on the meter. I need some Camaro wisdom. Thanks

Sounds like a bad battery connection. Even though you read over 12 volts without a current draw, a heavy power load with a poor connection can make it act like you're getting. Make sure the battery terminals are all clean. Also check the battery positive cable connection at the starter, the battery ground connection to the engine, and the engine to frame ground cable/strap. Also make sure there isn't any corrosion where the connectors are attached to the cables.

Is there a relay somewhere that it keeps tripping?

The horn relay and voltage regulator are junction points for accessory power. So you can remove the wires from them, clean everything up, and see if anything changes for the better. I've had the exact thing happen to me before, and it was a bad ground cable. Corrosion had formed between where the crimped end and cable connect (the end that connects to frame/engine). Do you have factory made battery cables, or the clamp on replacement battery terminal ends? Corrosion can form between there too.

Original cables, new battery.

Thanks for all the help. I will clean everything up and let you know.

Thanks Camaro 69

That was the problem. $25 in battery cables later and she fired right up.
You are like the Camaro Yoda.

Thanks Again.