GM Chevy Mid-Size Cars 1964-1988 Repair Guide

Design

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All Chevrolet engines, whether inline sixes (L6), V6 or V8, are water cooled, overhead valve powerplants. Most engines use cast iron blocks and heads, with the exception of some high performance 454s, which use aluminum heads.

The crankshaft in the 230 and 250 cu. inch 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 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 car makers. The Chevrolet built 229 and 262 V6s are also similar.

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. For example, in 1968 the 283 was dropped and replace by the 307, which is in effect a 327 crankshaft in a 283 block. And the 267, 305, and 350 V8s all share the same stroke, making crankshaft and bore dimensions, the main difference between the engines.

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 Chevelle, and feature many tuning modifications such as high lift camshafts, solid lifters (in some cases), high compression ratios and large carburetors. These big blocks engines are similar to their small block little brothers in basic design.

The 350 V8 diesel is derived from the 350 gasoline engines, except that the cylinder block, crankshaft, main bearings, connecting rods and wrist pins are heavier duty in the diesel (due to the much higher compression ratio). The 263 V6 diesel is nearly a 6-cylinder copy of the 350 V8, sharing the same bore and stroke and many engine components. Both V6 and V8 diesel cylinder heads, intake manifold, ignition and fuel systems are also different from their gasoline engine counterparts. Aircraft-type hydraulic roller valve lifters are used in the diesels.

The Buick built 231 V6 is the only engine used in the mid-sized Chevrolets which is substantially different. This engine follows Buick V8 practice in that its valve gear incorporates rocker shafts instead of the ball joint style rockers on the other engines.

 
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