Re: Ignition switch to starter intermittent
With the above Post 6 symptom and being a '69 Z/28, clutch switch can be a problem if not an open circuit elsewhere.
Ign sw replaced/adjusted on column and still hot start problem, I offer the following:
1. Move ground cable to the block as the present return path back to battery from starter case is through the block, the head, intake manifold, upper alt bracket, and finally, the cable. Shorten the path.
2. Check battery voltage during cranking or no crank. Battery voltage below 9.5 VDC, low charge on battery, either a too small battery, not enough recharge time, or too low of recharge voltage. Also, check voltage between solenoid stud and battery post, not on the terminations. Same goes for the return path, motor case to negative post. Measurement should be less than 1 volt during cranking. This measurement tells you the amount of voltage dropped across the current path. Do the same for the purple wire at the solenoid - stud to post measurement. Count the connections in this one circuit.
3. Battery cables too small of gauge/size. GM in their design to price thinking, installed the smallest cable size to get the car through warranty. Min size wire is 1/0 gauge with molded post clamp.
4. All the connections are low resistance as they cannot be accurately measured by the typical ohmmeter, one needs a low-ohmmeter to measure the resistance. Suggestion here would be disconnect each connection from battery positive post through the start circuit, through the starter and the ground path and wire brush the terminal rings and the item the rings are attached. This cleaning for the slip-on connectors of clutch switch would be a shot of contact cleaner.
5. Solenoid, the plastic end piece can come off as you know and one can rotate the copper bolts and the mating disc providing a 'new' contact surface.
As I stated about resistance, heat is its natural enemy. More heat, the higher the resistance, more current given up at the junction(s) or lack of wire size as heat, less current available for the starter motor.
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