Classic/Antique Car Repair/1937 packard no start
37 Packard when hot stops Runing.Coil is very Hot, Change coil it runs till that coil gets hot.useing 6v coil Napa one car Quest.Packard coil from kanter. all did the same thing got hot no spark.can you help Joe.
It may not be the coil itself although either one of the replacements you got are quality units. You should have a big, fat, blue spark when you ground the coil wire. If not, I would be suspicious of your coil, which could be breaking down internally, regardless of make. However, to make sure, try connecting a jumper wire from the main battery terminal on the starter solenoid, to the SW (+) terminal on your coil and then another jumper from the Dist (-) terminal of the coil to your grips on the head stud, as you describe. You will need a plug in the HT lead from the coil tower of course, and make sure that the plug is earthed against the cylinder head too. Remember to try other High Tension Spark plug wire leads too. Then, when you make and break the circuit as before, you should get a good spark, if not the coil is knackered!
For future reliability, I would be inclined to rewire from the ignition switch to the coil and from coil to distributor, I would also replace the High tension (plug wires) leads.
Finally, There is a list of other things about the original design that aren't helping to deliver a reliable spark. The plug wire manifold. All of the plug wires are stuffed through a sheet metal tunnel that promotes crossfire. No plug wire boots at the plugs. Frayed wires inside the armored cable from dash to distributor. (never liked that armored cable despite it's anti-theft purpose as a hot wire preventer)
If you check these items, I think you'll find your problem. I'm leaning toward the cable wiring myself but checking all of these areas will peel back the onion of potential causes and give you a great running and dependable car.
Let me know how this turns out.