There are several important numbers to identify a 356 engine. The first, and most obvious one, is the serial number, which uniquely identifies each engine. It is on the “third piece” of the case, or timing cover, below the generator stand (or on the generator stand if you have an early 2-piece engine case).
You will also find an engine type identifier, which was Porsche’s internal code to designate the different specification engines. The type number can be found on the right side of the case, near the center, on the perimeter bolt boss. It is just behind (relative to the car, not you) the fan shroud. So, look at an installed engine, looking beyond the generator stand, at the “bump” in the case casting where the two case halves join.
You may have to clear off a layer of oil and dirt to see it, but you will find a number such as “1600” or 616/1. Click here for a picture (the area to look is circled in blue). There is another number to the left, which is an internal serial number (sometimes referred to as a case casting number) used by Porsche when the engines were manufactured. Although it can be correlated to the engine serial number, data is generally unavailable. Serial numbers on four cam engines are on the left case half, above and to the left of the fan pulley