How to Identify a 351 Boss Engine
- 1). Count the number of bolts on one of the valve covers. The Ford 351 Cleveland, the 351M and the 400 cubic-inch all have eight valve cover bolts. Next, locate the thermostat housing. Unlike most engines with the housing is located on the intake manifold, the Cleveland engine's housing is located on the front of the block. These two factors identify a 351 Cleveland engine but not necessarily a Boss 351.
- 2). Locate the engine block casting number on the passenger side of the block, near the starter. According to My Boss 351, the casting number for Cleveland engines is D0AE-6015-L. This code identifies the 351 Cleveland block used in 1971 vehicles.
- 3). Check for four-bolt main bearing caps. According to My Boss 351, only Boss 351 blocks have four-bolt main bearing caps in 1971. Two-bolts mains are standard 351 Cleveland engines. The main bearing caps are located on both ends of the engine, front and rear, and have two or four bolts fastening them to the block. The main bearings are the crankshaft bearings.
