Its been wicked hot here in Denver and my 80 is getting harder to start. Sometimes I go out and it starts right up. More often though, it just makes one clicking noise when I turn the key, followed by nothing. I turn the key many times fast, repeating that clicking and every so often it turns the starter and it will start up. There is no grinding noise like a bad starter, and it is not a bad battery because I bought a new one, and it doesn't respond to a jump. A few weeks ago I discovered that my old battery was out of water, I thought that might be the problem but it wasn't. The battery connections are clean. Also, for the longest time now, when I start the car, my battery guage remains very low to the left until I rev up the engine. Revving it causes it to move (and stay) just to the right of the center. Has anyone lived through this problem? Are they related? What is the problem and what can I do? Thanks Tom

 

Check the cable from the battery to the starter. If thats in bad shape or shorted, that may explain the low charge (guage and clicking) You are most likely pulling in the solenoid, but not enough juice to crank the starter. Once under the alternator power, you will be ok, just not back carging the batter sufficiently.

 

ttt don't know what the big ears mean but they look

 

With an increase in temps you have an increase in resistance and according to Ohm's Law you have a decrease in voltage thus your starter solenoid won't engage.
Thats the easy part. Now you have to find the high resistance and go through all the connections in the car looking for looseness ,corrosion and possibly wires on the verge of braking. This is not to say that a simple starter/solenoid replacement won't cure all your problems but you can through a lot of money at this without any results if all along you have a bad connection
Two things will help: a wiring diagram and a piece of wire with 2 terminal ends that can reach from your S terminal on your starter solenoid to the positive post of your battery.
The first is to help you track down all the connections from the solenoid battery terminal around the eng to horn relays, firewall connectors, starter sw, neutral safety sw and back to the S solenoid terminal to activate the solenoid. Thats why I said you need a wiring diagram to trace this circuit since my description is only a general one.
The second thing you need is this piece of wire to help troubleshoot the system. With the wire installed you can now hot start the vehicle and bypass all the sw connections and wiring. When the car won't start just take the wire with the ignition on and touch it to the positive post to engage the starter solenoid. If this works it tells you the starter solenoid and starter are in reasonably good shape and that you have a problem with the circuit. If it doesn't work its time for a new solenoid and possibly starter. Take the whole unit to Auto Zone or someone else and have them check it out on a machine. When the wire is not in use tie back against the fire wall someplace This wire is only hot when the starter sw is engaged also be careful to take a piece of cardboard and blow out any lingering gas about the battery before hot wiring the battery post. A starter test sw is best but if you take precaution of ventilating the area you will be all right. Just be aware batteries give off Hydrogen gas and can explode if not careful.
Good luck Bob