Chevrolet 400 Engine Specs

The Chevrolet 400 is the largest-displacement factory version of the first-generation small-block V8 family and the one most closely associated with big low-end torque in a traditional small-block package. Introduced in 1970, it pushed the classic Chevrolet small-block architecture to 6.6 liters and gave the family a distinctly different character from the revvier 283, 302, or 327 engines.

Chevrolet developed the 400 by increasing both bore and stroke beyond earlier small-block norms, creating a torque-focused V8 that still used the familiar OHV architecture and compact external dimensions of the family. It was produced with a cast-iron block and heads and generally appeared in passenger cars and other applications where strong effortless pull mattered more than high-RPM personality. Factory power was typically in the 150 to 265 HP range depending on year, while torque was the real headline figure.

In enthusiast circles, the 400 is valued because it brings big-cube torque to the classic small-block world and provides a strong foundation for street-oriented builds. At the same time, it is more specialized than a 350 and needs to be understood on its own terms rather than treated as just another ordinary small-block.