Crocker motorcycles was founded by Al Crocker in 1936. They were the largest displacement and fastest motorcycles around for many years. Much more powerful than either Harley, Or Indians offerings. Crocker made his name by building speedway bikes until he decided to produce some road going machines. Though made in much, much smaller numbers, I think what Crocker achieved with his designs is much more significant than what the other manufacturers of the day produced.
and its a HEMI.