Chevrolet Full-size Cars 1968-1978 Repair Guide



All engines, whether inline sixes (L6) or V8, are water cooled, overhead valve powerplants. Most engines use cast iron blocks and heads, with the exception of some high performance 8-454s, which use aluminum heads.

The crankshaft in the L6-230 and L6-250 cu. in. 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 is gear driven. Relatively long pushrods actuate the valve through ball jointed rocker arms.

The small block family of V8 engines, which has included the 267, 283, 305, 307, 327, 350 and 400 cu. in. blocks, have all evolved from the design of the 1955 265 cu. in. V8. It was this engine that introduced the ball joint type rocker arm design which is now used by many vehicle 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.

The 396, 402 and 454 engines are known as the big blocks, or less frequently, the Mark IV engines. They are available in the high performance SS versions of the Chevrolet, and feature many tuning modifications such as high lift camshaft, solid lifters (in some cases), high compression ratios and large carburetors. These big block engines are similar to their small block little brothers in basic design, but parts cannot be interchanged between the small and big blocks.