1972 dart - stopped running while at 50 mph ? no warning
i am starting to suspect the wire that comes off the firewall going to coil negative , might be another part of the issue . it looks a little corroded where the wires are exposed . can that wire be tested with a multimeter ? or powered test light ? ballast connected or not ? key on or off ? cranking etc. ?
The BLUE wire from the firewall goes to the coil Positive.
The coil Negative, goes to the points.
The coil is just a transformer, that multiplies the battery voltage high enough to spark the plugs which is about 16000 volts or more. If you run the coil in reverse polarity, I have no idea how that will affect things; I've never tried it.lol.
To test for power at the coil +, the points have to be separated; otherwise the power runs straight thru the coil to ground, and the voltmeter reading will be wrong.. At key-on, with a cold ballast, you should have near battery voltage there. If you don't, your condenser may be bad; so the next test is to take it out of the circuit.
With the points open and the condenser out of circuit, both sides of the coil should have nearly the same voltage.
The ballast is a choke. When cold it lets most of the battery voltage thru. As it heats up, it chokes the incoming voltage down to in the range of 7 to maybe as much a 9v, while the regulator is pouring the coals to the battery.
You can test the timing chain slack using the fan to rotate the engine. You only need to rotate the crank a few degrees in either direction until you feel resistance, and then go the other way until you again get resistance. Watch the rotor; if it moves, you rocked it too far. Start over. If the belt slips, make it stop, lol.
With a new chain, and ideally, this should be ZERO degrees on the balancer. I have taken apart engines that had 10* rock on the balancer and still ran. 4 to 6 on a hi-miler is more common
Btw.
I have a 318 here with a jumped chain. The pistons came around and bent the valves; now it has no compression.
