No, this is a big block. In this original GM promotional film, we get the inside story on Chevrolet’s 396 CID and 427 CID Big-Block V8s for 1966.

The original Chevy Small-Block V8 introduced in 1955 was a tough act to follow, but after a couple of near misses, Chevrolet brought forth a worthy large-displacement companion V8 in 1965. Known variously as the Semi-Hemi, the Porcupine V8, and the Rat Motor, the Chevrolet Mark IV V8 (official name) was produced in 396 CID form in 1965, and in 396 and 427 CID versions for 1966. Offered in Chevy passenger cars and trucks for decades, the Big-Block engine family remains in production to this day in the Chevrolet Performance consumer crate engine line.

In this clip, an excerpt from a vintage dealer sales film, we’re treated to an introduction to the Big-Block lineup for 1966, starting with a brief, non-technical explanation of the engine’s distinctive canted-valve cylinder head. (The configuration was first used on the division’s 427 Mystery Engine in 1963—read about it here.)  Then there’s a click-through of available engines for ’66, from the basic 230 CID six to the top of the heap in Big-Block muscle that year, the 427 CID, 425-hp Turbo-Jet V8 with solid valve lifters and Holley four-barrel carb. The announcer is our old friend Joel Aldred, the Canadian broadcaster who became the voice of Chevrolet in the ’60s. Video below.