Thanks guys. I just reconfirmed that the base plate IS grounded (test probe clamp connected to neg side of coil, pointer on base plate results in normal bright light). I believe this confirms that the base plate ground wire is intact, leaving the points as the likely problem. Also, I’ve clearly seen that power was not moving from the movable point to the fixed point when apparently closed. I’m going to check today if I can buy the points set for this prehistoric machine. It will be tonight before I have time to work on this again.
@Caddyman: I don’t know how to identify the ballast resistor you mentioned, what does that look like and where would it be located? This is not another term for condenser is it? The condenser seems secure.
@Cougar: I definitely get 12 volts at the moveable arm of the points, but nothing on the fixed side when points are closed. Seems the contacts must be deteriorated though visually I can’t see a problem.
Geez, I was just about to give up on this unnecessary tinkering with my obsolete ignition system, but now with all these responses, I guess I have to persevere! Like I wrote way back at the beginning, I don’t need to get this thing running, I was just curious. ;~) Oh well, I’ve definitely learned something! Thank you all! I’ll post back in a day or so.
The ballast resistor maybe inside the coil or it may be mounted on the firewall, but it is not the source of your problem. If it is an external resistor, it will be a white(ish) ceramic block about 3" long a 1/2" square with a wire on each end. You will find it by following the wire from the positive terminal of the coil.
If the ballast resistor were bad, you would not get 12v to the coil or to the points.
Great. Using your test probe you have proven that power is getting to the hot side of the points and the grounded side of the points are actually connecting to ground. So when the test probe is touching the minus side of the coil and points are closed the test light should normally turn off because the points should be making the ground connection to the minus side of the coil and that connection point should now be at ground potential (no voltage). The coil windings are the load of the circuit. When the points open again the voltage will then be back on the minus side of the coil because the circuit is now open and the connection to ground is removed. There may be some plastic on the contact surfaces of the points that is preventing them to make contact electrically or the points really aren’t physically closing. Whatever the trouble is it should be easy to fix.
I cleaned up the old points, making sure that the underside of the points plate was shiny clean before installing and setting the gap. With that, I got the flashing of the test light on the neg post on the coil, so I cleaned the rotor and cap and tested for spark…there it was. With a bit of starting fluid, it fired to life momentarily. When I tried small amounts of gasoline in the carb, it started and ran a few seconds each time!
Tomorrow I’ll see how much work it will take to empty the gas tank so I can give it some good gas and actually drive it down the driveway. If anyone knows a safe way to provide an alternate small supply of fuel (the fuel line is easy to access), I’d like to try that instead.
Thanks everyone for all the excellent instructions. I would not have succeeded without all the generous assistance. I’m grateful to everyone who contributed.