Which jeep engine do I have (pics)?

[rob love]

The L and the F refer to the locations of the valve train in relation to the pistons. A flathead engine (like yours) is an L head. These engines were later redesigned for more horsepower by moving the intake valves into a larger head, which makes the intake flow more efficient. These were known as a F head.

Some guys get mixed up because of the F head and Flat head. They are not the same engine.

Long and short, yours is an L head (also known as a flathead.)