If you have the stock ign switch and firewall mounted coil with a single terminal in the engine compartment I suggest putting a volt meter on the coil terminal or the distributor terminal and measure voltage to ground to verify voltage. When points are open there should be battery voltage of 6v at that point. When points are closed there should be just over 0v measured. It would be ideal to verify when cranking that the supply voltage is not dropping below approx 5.5v. That is harder to do on that coil as the supply terminal is inside the car under the armored cable cap. If it drops near 5v the spark will be weak and if the plugs are dirty or fouled the spark may not be able to easily jump the gap.
If you have voltage remove the center high voltage wire from the dist cap and lay it near the block so the spark can jump to metal. Disconnect the small wire to the coil at the dist terminal end and touch the terminal wire end against the block. Be sure not to hold the bare terminal when doing this as there can be enough kickback voltage generated to give you a shock. There should be a spark generated each time the wire is touched and removed from the block.
With everything connected If there is no voltage at the terminal check the supply voltage from ign switch which goes to the coil terminal inside the car via the wire in the armored cable. If the voltage is continually near 0 and never makes a transition between 0 and 6v check for shorts in the distributor. If the dist has been disturbed internally, a short in the fabric covered flex wire between the points and outside terminal or a shorted capacitor is suspect. If you have overdrive there is also a small chance a relay or contact in the ign cutout circuit could be hung resulting in a ground condition. Disconnecting the wire coming from the OD relay to the coil will eliminate that possibility.
If the voltage is present but never drops look at the points and make sure they are closing.
If the voltage does fluctuate but is consistently somewhere between 6v and 0v verify the points are not burned or oxidized from years of sitting and check that the distributor has a solid ground to the engine block thru the mounting clamp.
If you would like a bit more info on how the point systems work there is an Ign system training manual you can download from the literature section.
packardinfo.com/xoops/html/downloads/IgnitionTrainingManual.pdf That particular manual is a Packard publication applicable to the 41-47 models but is a good tutorial for all the old point systems.
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