Ford Small-Block Engine Parts Interchange. George Reid

351M/400

      The 400 and 351M engines use the same raised-deck Cleveland block. This block has a 1.091-inch-taller deck height (10.297 inches versus the 351C’s 9.206 inches) to accommodate the 400’s 4.000-inch stroke. This makes a 351M/400 block easy to identify. However, most 351M/400 blocks have a Ford big-block bellhousing bolt pattern, which means you need to use a big-block C6 or Top Loader for a raised-deck Cleveland engine project. This is the same bolt pattern used for the 385-series 429/460-ci big-blocks but not for the FE-series 390/427/428.

      One Ford insider closely involved with Cleveland engine development said that the 335- series engine family was originally going to have a minimum of 335 ci, which explains the “335” designation. The 335 became 351 ci with the same bore and stroke as the 351W along with the same bore spacing.

      Cleveland blocks were designed for four-bolt main bearing caps, which didn’t happen until well into production. Ford engineers wanted more iron underneath for added strength without a skirted block and cross-bolted main caps. They also wanted an engine with minimal potential for leaks, hence the dry intake manifold and steel-plate front timing cover.

      Although Ford produced 302 and 351C engines in Australia, none of the Australian blocks was fitted with four-bolt main caps. Australian Cleveland blocks did not have traditional North American Ford casting numbers, though it is believed North American casting molds were shipped to Australia when 351C production ended in 1974. If you find a Cleveland block devoid of a Ford North American casting number and a “GF” foundry designation, you’ve found an Australian block.

       This is the 400 Cleveland block, which arrived late in 1971 for the 1972 model year. The 400 is identifiable by its narrow boss, which rises just to the right of the distributor bore here. The 400 and destroked 351M that arrived for 1975 both employ this block. (Photo Courtesy Tim Meyer)

       A bird’s-eye view of the 400 block shows a taller deck and the raised bosses in front. The raised thermostat bore is to the left of the distributor bore. (Photo Courtesy Tim Meyer)

       Underneath, the 400 block reveals its larger 3.000-inch main journals and D1AE-AA two-bolt main caps. This block can be converted to four-bolt main caps thanks to generous pan rails and main webs. T Meyer Precision Automotive Machining offers four-bolt main steel billet main bearing caps for the 351M and 400. (Photo Courtesy Tim Meyer)

       Side by side, the 351C (left) and 400 (right) blocks are easily identified. The 400’s taller deck and big-block bellhousing bolt pattern distinguishes it from the 351C. (Photo Courtesy Tim Meyer)

       Early Ford small-block castings prior to 1975 are cast, drilled, and tapped for a Z-bar clutch linkage. If you’re building a 1975 or later block, you have to find a bolt-on Z-bar pivot bracket, which is a Ford part.

       Your block prep regimen should include screw-in oil galley plugs in the interest of engine security.

       This is the one-piece rear main seal that arrived in December 1982 on all small-block Fords. To use a one-piece rear main seal block, you must use a crank devoid of the lip for a two-piece seal. Cranks with the seal lip can be machined down for a one-piece seal.

       This 400 block is a first-year-only casting with both big- and small-block bellhousing bolt patterns. This block is drilled for small block use. Your chances of seeing this block anywhere are slim. (Photo Courtesy Tim Meyer)

       All small-block Fords prior to December 1982 (1983 model year) have a two-piece rear main seal. The 351C, 400, and 351M never had a one-piece rear main seal.

      The orifice plate below the thermostat on the 351C engine block controls coolant flow to the thermostat and should never be removed. If you do, you will have thermostat malfunction and resulting overheating issues. Ford called this the “Controlled Bypass System.” The new coolant-control system provided improved cooling without frequent thermostat cycling. It also provided for improved warmup. When Ford introduced the 400, it eliminated the orifice plate, instead molding the Controlled Bypass System into the block.