We used to run flathead Fords with no air filters or, at the most, small wire mesh ones. Also, those engines had no provision for an oil filter. We also used to have to overhaul them every year or two, and spent about an hour scraping the mud out of the oil pan and valve area with putty knives.
The recommended time between valve jobs on the Lincoln V12 was something around 16K miles. They also used wire mesh filters because there was no room for a proper oilbath one like the Chryslers and Packards used.
I had wire mesh filters on my '49 Triumph and had to do a ring job on it after 2 years.
