"Headers pipes thin with age from heat, so your problem could be a combination of low voltage and heat soak. One place to check for voltage drop is the large bulkhead on the firewall with all the wires coming out, the engine harness unhooks from engine side. I have seen more then one have a bad connection."
Joe....Here are a few pics of that firewall connection. Look closely at where the wires go into the connector. Do you think that is plastic "goo" is from overheating wires, or maybe some type of "goo" that the prior owner (30 years ago) put into the connector base to help hold the wires in place? From the pics, what do you think of the condition?
Also, to unplug the connectors and look inside at the prongs/connection points, do you unscrew that bolt in the middle first?
When you look at the pics, there is a "white" wire coming out of the left middle, below the brown wire (with a red crimp connection). It is a kinda of a cloth covered wire with some frays going on......is this that famous "resistor" wire that goes to the ignition? Can a bad "resistor wire" get too warm and cause the "no start when engine warm" condition?
