One thing that happened to me: The rotor on my engine (1953 327) has a carbon rod to act as a resistor, to reduce interference with the radio. Those can break, randomly. Not sure that was true all the way back in 1940, but who knows what's on your car!
Check Ross' great video here:
Ross Video about Distributors and Setting the Timing Also it's great to get one of these to just double-check you are getting spark even while the engine is cranking over. They are great. I actually left it on one cylinder while I was driving around, no problems, helped me monitor whether things were changing when the engine warmed up.
NAPA - Inline Spark Plug TesterThis Post was from: https://packardinfo.com/xoops/html/modules/newbb/viewtopic.php?post_id=239655