I don't know if anyone's seen this, but it looks like somewhere along the way the old girl got new parts and a paint & polish job.
1940 Maytag model 72 motor
MHF
1940 Maytag model 72 motor
MHF
!!!I found a website that has mechanical drawings and parts lists for this engine. It's a very interesting if antiquated design. Without roller bearings you'd still have to run a fairly oil-rich mixture, but I think it could make some decent power with a few improvments.
Maytag Model 72 Engine Drawings
It appears to have a timed intake flow path through an L shaped path in the crankshaft....I see some room for improvement there as well as the pathways leading from the crankcase to the cylinders. I'm guessing the airflow into the crankcase to get it past the fuel jet has a few tight turns as well. Running a regular carburetor instead of the factory sytem which basically uses the fuel tank as a carburetor fuel bowl, would eliminate the need for a lot of those torturous passages and allow it to breath better. Add a well designed pair of expansion chambers and you might get it to rival a HF engine
I hope I can find a cheap one in decent shape to experiment on.
MHF