Home Auto Repair How to Decode the GM Engine Block

How to Decode the GM Engine Block


Every GM engine is stamped with an eight-digit code. When you translate this information, you can find out when and where the engine was made. In addition, the engine suffix can be cross-referenced to verify the year and body style of the vehicle the engine was built for. The engine code is different than the longer VIN number, which includes information on the model, body style and assembly plant.

Step 1

Locate the engine block code. This series of seven to eight digits begins with a letter and is stamped directly on the engine. Look behind the distributor on the passenger side of the block if it is a six- cylinder GM motor. On a small block GM V8, it is stamped in front of the cylinder head on the passenger side. The code is stamped above the timing chain cover on big block V8 engines.