I concur with Rusty on this one.
I started a similar thread quite a while back in the "S" forum (because I was referring to the "universal" motors in my AF 300 and 310, which have neither smoke or sound). I had often heard these engines would run "better" and cooler" on DC and wanted to see for myself.
I came over from HO, and have several nice "power packs", but I found that the amps(?) needed to run these old open-frame motors would typically over load those packs. I eventually found an older (pre-zip code) MRC unit that, for whatever reason, is fully capable of running those Flyer locos without shutting down...it also works great with my DC-powered All Nation Ten Wheeler.
Having said all that, I usually run those Flyer engines in AC with a small-ish MRC 027 unit; I like it because unlike post-war Flyer or Lionel transformers, it begins at 0 volts...
Mark in Oregon