This is a Riley 4-Port overhead valve head on a Model A/B block. This F head design rocker arm head is likely one of the fastest volume-produced heads made for the Model A/B Ford. It features two intake valves per cylinder and one exhaust valve in the block.
Riley 4-Port heads had excellent breathing characteristics - Riley claimed the upgrades could produce as much as 160HP at 4500rpm. The 4-Port OHV head was sold and raced all over the country in the 1930s.