- Big-block engine
A large V-8 engine produced in the '60s and '70s. It typically has a cast-iron block and head and is fed by a carburetor. Contrasts with small-block engine. Although both engines were of the same displacement, the big-block engine was larger in overall size than the small-block engine. Thus, as vehicles grew smaller and more equipment was stuffed into the engine bay, the small-block engine was favored over its larger brother.
( http://www.motorera.com/dictionary/BI.htm#Big-block_Engine )

- Small-block engine
During the '60s and '70s, GM, Ford, and Chrysler made two types of V8 engines of the same displacement e.g., 350 cu. in. small-block and 350 cu. in. big-block. The small-block engine was an enlarged smaller displacement engine (e.g., GM enlarged the 283 to 327 then to 350 by boring the cylinders). The big-block engine was a completely different basic engine size even though it displaced the same as the enlarged small-block engine. Thus, as vehicles grew smaller and more equipment was stuffed into the engine bay, the small-block engine was favored over its larger brother.
( http://www.motorera.com/dictionary/SM.HTM )

- Block
1. That part of the engine containing the cylinders.
2. Rectangular, square or cylindrical deck spacer, often identified by its location within a pallet as corner block, end block, edge block, inner block, center block, or middle block.
( http://www.motorera.com/dictionary/BL.HTM )