All Chevrolet engines, whether an inline 6 (L6), a V6 or a V8, are water-cooled, overhead valve powerplants. All engines use cast iron cylinder blocks and heads.
The crankshaft in the 230 and 250 cid inline 6-cylinder engines is supported in seven main bearings, with the thrust being taken by the No. 7 bearing. The camshaft is low in the block and driven by the crankshaft gear; no timing chain is used. Relatively long pushrods actuate the valves through ball-jointed rocker arms.
The small block family of engines, which includes the 283, 302, 305, 307, 327, 350, and 400 cid blocks, have all sprung from the basic design of the 1955, 265 cid engine. It was this engine that introduced the ball-joint, rocker arm design, which is now used by many car makers. This line of engines features a great deal of interchangeability, and later parts may be utilized on earlier engines for increased reliability and/or performance. In 1968, rod and main bearings were increased in size on the small-block family. The 283 was also dropped in that year and replaced by the 307, which is in effect a 327 crankshaft in a 283 block. The 327 and 350 engines share the same cylinder block, with the difference in displacement being provided by a longer stroke crankshaft. The 305 and 350 cid engines remain as the most common V8s.
The 396 and 402 cid engines are known as the Mark IV engines or big blocks. These engines feature unusual cylinder heads, in that the intake and exhaust valves are canted at the angle at which their respective port enters the cylinder. The 396 cid engine was used from 1967-72. The big-block cylinder heads use ball-joint rockers similar to those on the small block engines.