General Motors uses a systematic engine identification system that requires consulting a Chevrolet engine ID number listing. The information provided is useful, but a problem with Chevrolet engine identification is that many blocks were used for similar engines of different displacement. Cross-referencing casting numbers from other engine components can also be misleading as many of these parts were interchangeable with other engines. All this aside, the GM/Chevrolet system will tell you the vehicle the engine was intended, the year and horsepower as well as other technical identification information.
Locate the engine ID number. On small-block V8s, it is located on the passenger-side front of the engine block, right below the cylinder head. Big Block V8s normally have the number in the front, near the timing chain cover and in-line six-cylinders locate it on the passenger side behind the distributor. V6 engines generally follow the small-block V8 pattern.