Kevin:

Great suggestion; my problem is that I just saw my 1940-120 for the first time a few days ago, and it has small hubcaps on it that do not look the same as what I have seen in pictures of other 1940 Packards. The Packard script painted black crosses the Packard hexagon painted red in the center of the cap. These hub caps fit well on the 16" wheels but I think they must come from an earlier year, or perhaps from one of the senior cars.

So I could give you a photo of these hub caps, but can't vouch for whether or not they are correct for my year/model.

That may be an interesting side project for everyone to take a picture of their hubcaps and send them it, then I could turn that into a kind of hubcap-timeline.

Just throwing out ideas.

Is there some site that may show photos of the various style hub caps that were correct for Packards throughout the years. Perhaps I could search through some of the various year's brochures, but I thought that there might be some place to see that various year's styles side by side?

I can imagine the frustration. The coil should be easy to check: no spark = no engine runnin'. If you consider the history of Packard coil locations from the early 30's to 40 you will note from atop the engine to aside the engine to the horn bracket and finally back to the firewall in 41. Does that give you a sense that hot coils are not a good thing? Is there such a thing as a "weak" coil? I am told so, but I am not an expert in this area. Obviously a fresh set of points and condensor are cheap and easy.
Spark Yes, Fuel No = Fuel delivery issue. Do you have a fuel pump and/or a carburetor heat shield? Is the insulator gasket present between your carburetor and the intake manifold (its 1/4" thick, not just the thin gasket), along with a heat shielded fuel line. These are elements of the street term "vapor locking" which with todays alchohol fuels makes our cars more susceptable to fuel "boiling" problems.
Fuel pump strong? Not normally heat affected from my understanding. Is there a fuel filter that needs changing somewhere in the system? Please consider properly installing an electric "backup" pump.
Finally, and this is important - check the heat choke valve in the exhaust manifold - that heat spring weighted shaft thing above the exhaust pipe. If this is stuck in the closed position, as soon as the engine really starts to warm up, you could be diverting a huge amount of heat up, where you don't want it any more, contributing to cooking the fuel in the carburetor.... Well, this is an open forum for armchair quarterbacks, so that's my .02 worth. With a few more clues, I am confident you will get more than a second opinion.

HH56
Thanks for the response. I do have a clear bowl filter just ahead of the carb, and it does not appear to be void of fuel when this sputtering occurs, so I am less inclined to think that it is a fuel starvation problem, but your example may have some merit so I'll have to check the entire fuel line more closely.

Peter, I know Killarney well. I used to work as a game warden in the waters just west of Killarney in Fraser and Baie Finn (the only inland fjord in the world apparently) If you get a chance fly over Baie Finn and especially the Pool at the northern end where Ralph Evinrude , of the outboard engine family and the actress Francis Langford once owned an island. I now live at the west end of lake Superior or about 600 miles west of Killarney as the crow (or Lake?) flies. If you do get a chance to come here let me know and I am sure I can show you some sites you will enjoy. BTW thanks for the info on my Super Clipper. It's still only getting 15mpg but at least I know that is about all she will deliver.

Very good point, because the ball can't drop back down to activate switch if the cam isn't just right.

Could be vapor lock but I'd think it would have to be awfully warm to act up that quickly--unless the steel tube is right on the exhaust manifold. Do you have a fuel filter where you can see if any gas present?

I had a very similar problem on a 54 and it turned out to be the flex fuel hose was old and brittle. Apparently the inside lining was cracked and loose. Suction was enough to periodically let a piece move and close off. Without the engine running, it would relax and open the line again.

And, as you said, the coil could also be acting up when hot.

All of the possibilities listed above are good places to look. However, another possibility is that the throttle linkage is adjusted too tight trying to force the linkage against the idle stop. My 22nd series had the problem. I loosened mine slightly and it has worked fine since. It's an easy thing to check. Who knows, it might help.

I had a radiator shop in WV re-line my 1948 20 gal tank for about $50; I thought it was very reasonable.