The casting ID "D7TE-A3B" identifies the block as a 1977-1982 Ford 351M/400 truck engine block.
The 351M and 400 engines were derived from the 351C, and are all considered part of Fords "335 series" of engines.
The 400/351M was a raised-deck (1-inch taller) Cleveland with larger 3.000-inch main journals (which made it taller and wider than the 351C) designed to accommodate the 400’s 4.000-inch stroke.
The 400 debuted for 1971 to replace the 390/428 FE big-block in full-size Fords and Mercurys. For manufacturing cost efficiencies, more than anything else, Ford destroked the 400 to 3.500 inches to achieve the 351M for 1975.
The 400 Cleveland is a “square” engine, meaning it has the same bore and stroke dimensions. The tall-deck 400/351M has 351C-2V heads with huge, open 76.9-cc chambers, which makes them a poor choice for any Cleveland engine project because they lose compression and are prone to pinging and detonation due to poor quench.
Another important issue to remember with the 400 and 351M engines is their bellhousing bolt pattern. Most 351M and 400 blocks have a big-block bellhousing bolt pattern like the 385-series 429/460 engines. However, some were produced with both the big-block and small-block patterns, making them compatible with both types.
Although the 400/351M has a reputation for being a low-emissions slug from the 1970s, it is capable of making incredible amounts of power when fitted with 351C-4V or good aftermarket cylinder heads and induction. And if you’re going to build a 351M, fill it with as much displacement as possible for best results.
Learn more about the 351M and 400 engines at Cartechbooks.com and Fordmuscle.com.
Tip! Learn how to decode Ford casting numbers system and understand engine size and how it affects your car-buying decision.