The Ford 351M V-8 engine comes from the Cleveland 335 series. The 351M was first produced in 1975 and replaced the 351C, in order to provide better use for larger sized cars. In 1977 these engines started being placed in light weight trucks. The "M" doesn't symbolize anything. It was only used to distinguish the motor from the 351W, which stands for Windsor. However, individuals soon began to refer to the "M" as modified.
The 351M is merely the same as the 400 engine. The 351M was created for the purpose of shortening the "throw" of the crankshaft on the 400, which is the same as the 3.5 inches used in the 351C. To go along with the smaller sized stroke, the compression ratio was raised to an 8.0:1. Therefore, the only difference in the 351M from the 400 is the size of the crankshaft and piston.
The 351M has a combination of the Cleveland block and heads, along with the Windsor crankshaft components. The block is made from the powerful 351 Cleveland with a C-6 pattern transmission bell housing.
The 351M has a four-inch bore, as well as a four-inch stroke. It has a 400 displacement; equaling 402 cubic inches. The 351M is equipped with a two-barrel carburetor, a cast-iron manifold, along with hydraulic lifters.
