The Ford Inline Six 250 is a 4.1L 250 cubic inch straight six-cylinder that was the optional engine available with the 1969 Ford Mustang and medium-sized Ford cars (such as the Ford Maverick) in the 1970 production year. The Inline Six 250 would become the standard engine offered by Ford with their Mustang in 1971 and was rated at the time for 155 hp. This same engine would be rated at 98 hp in 1972 and this rating would drop to 88 hp in 1971. You can recognize the Inline Six 250 by five freeze plugs on the side of the engine block and the seven main bearings included with this engine. It has the starter mounted low by the oil pan rail and six bell housing bolts as in previous Ford Inline Six engines.
The Ford Inline Six 250 is essentially an Inline Six 200 that has had the stroke increased from 3.126 inches to 3.91 inches. These changes to the Ford Inline Six 200 have the effect of increasing the horsepower of the original Ford Inline Six 200 engine to 155 hp and 240 ft lbs of torque.
Around the same time, Ford Australia introduced the 2V cylinder head, which was nearly identical to the old integral “log head” intake, except for an aluminum intake mated with a removable Stromberg 2V carburetor. This form of the Inline Six 250 sports a more efficient exhaust manifold that allowed it to breath easier and resulted in this form being rated for 170 hp. The cylinder head adjustment became popular, and was brought over to North America by racing enthusiasts.
In 1976, Ford Australia began phasing out the Inline Six 250, and it went out of production in 1980.