Help with a 1965 Pontiac 2+2 cutting out (no spark)?

Question

I have a 1965 Pontiac 2+2 convertible, and have an intermittent problem I can’t get to the bottom of. The car runs very strong and starts with no problem. But every so often the car just dies (like the ignition switch is turned off). It happens sometimes when idling, it happens sometimes when running down the road, just whenever it feels like. If I set for about 10 minutes it starts right up and will run great, sometime for days sometime for 5 miles. I checked and when the car dies there is no spark. I have replaced the battery, the starter motor and solenoid, the ignition switch, the coil, and the condenser, the spark plug wiring including the coil to distributor wire. Has anyone ever experienced anything like this happening? I am at a loss and in the need of help. Thanks!

Answer 1

my first guess would have been the ignition coil breaking down from heat but you say that has been replaced.
many times there is a breakdown in the ignition switch ( not the lock cylinder but the switch itself )
that would be my next guess
if it happens again i would see if there is power going to the coil.
if there is not, it would again point to the ignition switch

Answer 2

on the older pontiac's there is a ceramic solenoid that is mounted on the firewall. It has a wire that connects to each side of it. The back side of the solenoid is just a coil spring. If the solenoid is old and the spring has rusted thru, the car will run until the spring heats up and it will contract causing the car to die. Once it cools it connects again. That would be my only guess if you have replaced the coil.

Answer 3

Split the wiring harness at the firewall & check for a burnt wire end. If OK, then check for power on the "+" side of the coil. There is a resistor wire running to the positive side. May have to replace that wire.
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