When trying to identify a Small Block Chevy engine, one of the most important things to look for is the stamp numbers on the pad near the front edge of the cylinder head. These numbers are known as the 'machining code' or 'build spec code', and they provide valuable information about the engine's specifications and date of manufacture.

The machining code typically consists of three letters followed by a series of digits, with the last six digits being the Vehicle Identification Number (VIN) of the vehicle the engine was installed in at the assembly plant. The first two letters of the code indicate the type of engine block used, while the third letter indicates the power rating and other specifications.

For example, if the machining code is NTX5467, it would indicate that the engine is a 1977 model year Small Block Chevy with a specific power rating and set of specifications. The 'NT' prefix would identify the engine as a car (as opposed to a truck or pickup), while the 'X' suffix would indicate the power rating.

In addition to the machining code, Small Block Chevy engines also have a casting number that is stamped into the block near the rear extension. This number provides information about the engine's displacement, horsepower, and other specifications. However, it does not provide a direct date code, unlike the machining code.

Prior to 1970, Small Block Chevy engines used a two-place machining code, but this was later replaced with a three-place code that started in 1970. The 'C' prefix indicated cars, while the 'T' prefix indicated trucks and pickups.

While it is possible to decode the casting number of a Small Block Chevy engine, there are no known decodes for the size of the engine that is cast into the driver's side block skirt. This information may be important for enthusiasts who want to restore or modify their engines, but it is not typically necessary for everyday use.

Overall, understanding how to read and decode the stamp numbers on a Small Block Chevy engine can provide valuable information about its specifications and date of manufacture. With this knowledge, enthusiasts can better identify and appreciate these iconic engines, which have been used in countless vehicles over the years.

Small block chevy stamped number lookup