* Displacement: The most obvious difference is the displacement. The 360 is, as the name suggests, 360 cubic inches, while the 390 is 390 cubic inches. This difference comes from a larger bore (the diameter of the cylinders) in the 390.
* Bore and Stroke: The 390 has a larger bore than the 360, resulting in the larger displacement. The stroke (the distance the piston travels) might also be slightly different, though the exact figures vary slightly depending on the year and specific application.
* Power Output: The 390 generally produced more horsepower and torque than the 360. The exact figures vary depending on the year and specific engine configuration (carburetion, camshaft, etc.), but the 390 was always the more powerful of the two.
* Block: While both are big-block Fords, there might be some subtle differences in the block casting itself between the 360 and 390, though externally they look very similar. This is something a serious engine builder would need to consider for parts interchangeability.
* Applications: While both were used in F-100s and other Ford vehicles, the 390 was often found in heavier-duty applications or higher-performance versions due to its higher power output. The 360 might have been a more common choice for lighter-duty trucks.
In short, the 390 is a larger, more powerful version of the 360. They share a family resemblance, but are distinct engines with differing performance capabilities.
