Chevrolet's six-cylinder engines are easily identified due to Chevy's efficient engine numbering system. The code is seven to eight digits long, consisting of numbers and letters. The suffix gives the year vehicle, horsepower and transmission pairing, while the prefix gives the date and location of manufacture.
The numbers appear on the engine block, behind the distributor assembly. On earlier 1940s and 1950s models, the engine number may appear next to the dipstick. A typical Chevrolet engine number will read V0225FF; the suffix may consist of either two or three letters---in this case, "FF."
Check the engine code suffix against a Chevrolet code listing. The engine number V0225FF translates as follows: "V" means it was built at the Flint, Michigan, engine plant, "0225" represents the date of manufacture (February 25) and "FF" translates as a 1965 230-cubic-inch displacement with 140 horsepower.
Chevy six-cylinders from 1941 to 1957 follow a slightly different system that has more variables within the number. For instance, the letters A through F denote an engine built in the Flint, Michigan, engine plant, versus "V" for later engines. Also, locating earlier code listings may require consulting a Chevrolet parts department. With these minor differences, the code system essentially remains the same.