The Ford Inline Six 300 in reality was just a 240 cubic inch Ford engine with a longer stroke—the main difference being the dimensions of the block and the rotating assembly. It has seven main saddles and timing gears instead of a chain or belt.
The Inline Six 300 was first offered in the 1965 production year for full-sized cars, F-series trucks, and heavy duty hauling vehicles. It became the standard engine included in F-series vehicles in 1978, was rated for 114 hp, and replaced the Inline Six 240 as the main engine of the F-series line. This was due to customization and power-increasing options that could be attached without modifying the original design.
The Ford Inline Six 300 was implemented in bigger vehicles, including dump trucks up to 20,000 pounds, during the late 1960s and early 1970s. The inclusion of a heavy duty exhaust manifold with greater flow allowed these work trucks to operate at rates of 3 to 4 thousand rpm. Reports are that these manifolds have a greater flow rate than the electronic fuel injection manifolds and even some headers.
The horsepower rating of the Inline Six 300 was increased in the early 1980s, before the implementation of fuel injection, to about 122hp. By the late 80’s, with new advancements, the output reached 150hp. At that time, it included a removable intake manifold with optional fuel injection, along with a heavy duty exhaust manifold. The Inline Six 300 continued to be popular from 1964 to 1996 for vehicles, along with wood chippers, tractors, ski lifts, and power generators.
The Ford Inline Six 300 ended its life as a production engine in 1996 and was replaced by the Essex V6 powerplant in Ford F-Series vehicles.