Analysis of information sources in references of the Wikipedia article "BMW 801" in English language version.
The Jumo 213 had a three-valve head, but a four-valve head was in development for the "J" version. However, the Jumo 213A is documented as itself having superior high altitude performance at that particular point in time, although the DB 603 was later developed with equal or better features.
At the recent international meeting at Zürich, several of the successful German machines were fitted with the new Junkers 210 petrol engine...Three valves per cylinder are provided, two inlets and one exhaust, operated by push rods and rockers from a single camshaft.
The Jumo 213 had a three-valve head, but a four-valve head was in development for the "J" version. However, the Jumo 213A is documented as itself having superior high altitude performance at that particular point in time, although the DB 603 was later developed with equal or better features.
