Buick engines are relatively easy to identify, although the myriad stamped numbers can be confusing. In addition, conventional references to specific engines may prompt Buick owners to misidentify engines. For example, the commonly referred to Buick 445 V-8 is not a 445-cubic-inch engine, but featured the 445 foot-pound torque rating of a 401-cubic-inch V-8.
From the mid-1930s to the early 1950s, Buick earned a reputation for producing powerful in-line eight-cylinder engines. It produced straight-eights in cubic inch displacements of 233, 235, 248, 263, 278, 320 and 345. In 1953, the automaker introduced the nailhead V-8. Owners dubbed these V-8s "nailheads" for their small valves. Cubic inch displacements for the nailheads were 264, 322, 364, 400, 401 and 425. In 1961, Buick's small-block V-8s arrived in displacements of 215, 300, 340, and 350. Buick replaced the nailheads in 1967 with the big-block 400, 430 and 455 V-8s.
Engine identification casting numbers on in-line eight-cylinder engines produced from 1935 to 1952 are on the right side crankcase. Buick Series 40 and 50 feature stamped numbers on the passenger side near the front of the engine. Series 60, 70, 80 and 90 are on the right side near the rear of the engine. A Series 80, for example, will have a number similar to 8-3396937. The number "8" denotes Series 80.
Model year 1953 to 1956 Buicks equipped with the nailhead V-8 featured engine serial numbers stamped on the edge of the left cylinder bank above the centre of the exhaust manifold. A 1954 Buick Series 50 will have a number similar to V273956-5 with the "5" identifying the Series 50. Later Buicks, such as any 1962 model, will have "2I" or "4I" stamped in addition to the number starting at 1349046 to identify the 401 V-8 equipped with a two- or four-barrel carburettor.
The serial number and "JL" production code for the 198 V-6 is at the front of the right cylinder head. The 225 V-6 has the serial stamped on the left front portion of the crankcase. The production code, for example, of "KH" denotes a standard 225. The 1968 and later 250 V-6 has the serial number and production code stamped on the passenger side of the engine near the distributor.
The production code for the 215 V-8 is in front of the passenger-side cylinder head and stamped upside down. The 215 has "JM" stamped on the engine. The 300s and 340s' serial numbers are at the front of the crankcase below the rocker arm cover. The production code is on the passenger side above the centre of the exhaust manifold.
The serial numbers and production codes for the 400 and 430 V-8s are on the right side of the engine at the exhaust manifold until 1967. Serial numbers for 1968 and later Buicks are near the front spark plugs with the production code near the rear two spark plugs. The 1969 Buick 430, for example, has a "RD" production code near the rear spark plugs and the serial number next to the front plugs. Model year 1977 to 1979 Buicks with the 403, for example, have six-digit serial numbers.