Ever since 1964, Ford Motor Company has placed identification number tags on each of the engines it has built. Alternatively, counting the number of bolts on the valve cover of the engine gives the Ford engine's general family.
The identification tag is a series of numbers and letters that can identify everything about the engine, from the month and year when it was built to the Ford vehicle to which it belongs. For a six-cylinder engine, the identification tag is located under the coil-attaching bolts. For Ford engines with eight cylinders, the tag is in one of four different locations. For most of these engines, it is located under the coil-attaching bolts, but it can also be under the dipstick tube, under the heat indicator bulb or under the carburetor-attaching stud.
Counting the valve cover bolts is the quickest way to identify a Ford engine, but it doesnt tell specifically which engine it is. Only two bolts were used on Ford engines built between 1954 and 1964. This was before the implementation of the identification tag system it now uses, so the only way to tell if an engine predates 1964 is the number of bolts or simply the exclusion of a tag anywhere on the engine.