1. Engine Number:
* Pre-1984: The engine number will be stamped on the right side of the engine case. The first two digits of the number represent the year of manufacture. For example, an engine number beginning with "79" would be from 1979.
* 1984 and newer: The engine number is stamped on the left side of the engine case. The first three digits of the number represent the year of manufacture. For example, an engine number beginning with "984" would be from 1984.
2. VIN Number:
* The tenth digit of the VIN number represents the year of manufacture. A "1" represents 1981, a "2" represents 1982, and so on.
3. Casting Numbers:
* Pre-1968: The casting numbers will be stamped on the engine cases. These numbers can be cross-referenced with a Harley Davidson parts manual to determine the year of manufacture.
* 1968 and newer: Casting numbers are less reliable, as they may have been used over multiple years.
4. Other Clues:
* Engine design: Certain engine features, such as the cylinder head design or the type of carburetor, can be used to narrow down the year of manufacture.
* Accessories: Original accessories, such as the air cleaner or the exhaust system, can sometimes be used to determine the year of manufacture.
Important Notes:
* It's important to consult a reliable Harley Davidson parts manual or an online resource for accurate information.
* Some engines may have been re-built or modified, making it difficult to determine the original year of manufacture.
For the most accurate determination:
* It's best to contact a Harley Davidson dealership or a reputable motorcycle mechanic.
* If you're unsure, it's always best to err on the side of caution and assume that the engine is older than it might appear.
