From 1977 to 1982, the M-block (351M/400) V8 engine was a
mainstay of Ford
light truck powerplants. During that period, the M-block 400
was the largest
engine available in any Ford 4x4 truck. In the 1978 and 1979
the 351M and 400 were the only engines offered in Ford’s new,
The following sections provide some background on the M-block
The 400 was introduced in 1971 as a
longer-stroke variant of the
351 Cleveland, and it would be the last pushrod V8 engine ever
designed by the Ford
The 335 Engine Family
There were two engine types in the 335
series engine family, the 351
Cleveland (351C) and the “M-block.” There were several minor
variants of the 351C
engine (including the basic 2V and several high-performance 4V
versions), but there
were only two M-block variants — the 351M and the 400.
Demise of the M-Block
The ultimate cruel irony in the M-block’s
history was that it was so
well adapted to first-generation emission control systems, it
was not easily updated to
work with more modern engine management systems, and it was
dropped from production at
the end of the 1982 model year.
An M-block engine in factory trim has vast,
untapped power potential.
It is smaller and lighter than a 385-series big block (which is
why it was developed in
the first place), and when properly built, the M-block 400’s
output is comparable to
most big blocks.
M-block engines were used in most of Ford’s
mid-size to full-size
cars and station wagons from 1971 to 1979, as well as in pickup
trucks and Broncos
from 1977 to 1982.