See Figure 1
The engine serial number is stamped into the right front side of the engine block. This number identifies the engine family, application and build sequence of the engine. The engine number should be used any time engine parts are purchased; many parts within engine families are unique to the family and not interchangeable with other engines.
For example, the engine number ES3-2900001 for a 1985 Accord, breaks down as follows:
Meanings of numbers change from model to model and year to year. It isn't necessary to know what each digit means as long as the complete number is available when buying parts. From 1987 on, engines use a 5 character family designation, such as B21A1 or A20A3.
In this book, when specific engines must be identified, we will use the family designation (all the characters before the dash in the engine number). In more general cases, we'll use the more everyday designations such as displacement and/or fuel and emission system. An example would refer to all fuel injected 2.0L engines or all 1.8L engines except California vehicles.