Re: 67 Camaro keeps dying
On our 50+ year old cars, corrosion is the most common problem in the electrical system.
Grounds: I recommend you clean all of the ground connections where they bolt to the engine, body, and frame. I clean the lugs and frame / body area with 180 grit sand paper and then apply NO-OX to both surfaces before bolting the connection back using new star washers. The conductor from the battery to the body (fender) is a common problem as well as those at the voltage regulator and horn relay. Many times the braided ground conductors from the body to the engine and frame are eliminated with a engine swap as they are a PIA and unsightly - NOT a good idea in my opinion.
Capacitors: These are needed only if you play the original radio on AM. These capacitors fail over time due to internal construction and can cause a short to drain the battery. The only capacitor needed (in stock wiring) is internal to the distributor to the points.
Firewall connector to fuse box: Remove the connectors and clean any corrosion from the pins. Lightly coat with NO-OX and reinstall.
Charging system: If you charge the battery and it runs fine until the battery gets low, you have bad diodes in the alternator or a bad voltage regulator. Use you multimeter to check for voltage draw when the engine is off and all accessories are off.
Bolted positive 12v connections: These corrode at the starter, alternator, horn relay, etc. They may work with a fully charged battery, but fail when the voltage gets low. You still need to find why the charging system is not keeping the battery fully charged.
At this point, you need to start testing each circuit for a short. Pulling the fuses and doing ohm tests and amp draw tests.
The only answer to your problem is slow meticulous troubleshooting and maintenance of the electrical system.