Is That a Big Block Under the Hood?

James Kraus

Plymouth 361 cubic inch (5.9 litre) SonoRamic Commando Big Block V8.

Pity the modern man. Increasingly put upon from seemingly every side, many seek solace in the days of yore when two adjectives in particular were highly prized; Muscular and Big

Therefore, it should come as no surprise that many of today’s auto enthusiasts; pining for a return of their testosterone-fueled youth, decide that all would be rosy again if they were to just buy an old Muscle Car with a Big Block.

As a result, nearly every American car ever built with an eight-cylinder engine is now described as a Muscle Car. This is entirely erroneous and was debunked earlier at Auto Universum.

Let’s review just what a Big Block is and what the term means. First; and most important, it is NOT a synonym for Big Engine. An 8.2-litre, 500 cubic-inch Cadillac V8 is a big engine (indeed a very big engine); but alas, was not a Big Block. On the other hand, a Ford 332 V8 was in fact a Big Block.

Ford 332 (5.4 litre) Interceptor Big Block V8.

A Chevrolet Camaro 396 had a Big Block, but a Pontiac Firebird 400 did not. Buick and Oldsmobile 455s are Big Blocks, but a Pontiac 455 is not. A Chevrolet 348 was a big block, but a Chevrolet 350 was a small block. Confused?

At one time, bragging about owning a Big Engine was enough, but lately it seems also rather important to proclaim possession of a Big Block.

The terms Big Block and Small Block came into popular usage in 1958 when Chevrolet, Ford and Plymouth began offering two entirely different V8 engine families. Chevrolet had their original Turbo-Fire V8 in 283 cubic-inch form alongside a brand new 348 Turbo-Thrust W-Series V8, Ford had their 292 Y-Block V8s and their new FE series Interceptor 332 and 352 Special V8s, while Plymouth proffered a 318 A-Series V8 and a 350 Golden Commando B-Series V8.

Chevrolet 348 (5.7 litre) Turbo-Thrust Big Block V8.

Within a few years engine choices expanded so that in 1964 Ford for example, offered 260 and 289 Challenger Small Block V8s and 352, 390 and 427 Thunderbird FE Big Block V8s.

Thus, segregating engines and engine families into Small and Big Block categories became useful shorthand. Describing a motor as a Big Block wasn’t meant to imply ancient mystical powers, it was simply to indicate that the engine in question was built using the larger of two available block castings.

As engines grew in size, Small Block families expanded to the extent that overlap with smaller Big Blocks occurred. Hence, displacement is not directly correlated with block size.

As an example; a 400 cubic-inch Chevrolet Turbo-Fire V8, larger in displacement than Chevrolet 348 and 396 Big Blocks, was actually a Small Block V8, bored and stroked to its limit. A big engine by any standard, but emphatically not a Big Block.

Oldsmobile 425 (6.9 litre) Toronado Rocket Big Block V8.

Here is a list of Auto Universum certified Jet Age Big Block engines:

AMC: 327 (1966 only)

Buick: 364, 400, 401, 425, 430, 455

Chevrolet: 348, 396, 402, 409, 427, 454

FoMoCo: 332, 352, 361, 383, 390, 406, 410, 427, 428, 429, 430, 460

Mopar: 350, 361, 383, 400, 413, 426, 440

Oldsmobile: 371, 394, 400, 425, 455

Ford 400 (6.6 litre) Medium Block V8.

Occasionally, engine blocks came in Medium as well as Small and Big. If you were buying a 1972 Ford Galaxie, you had a choice of a 351 (Windsor-series) Small Block, a 400 (335-series) Medium Block and a 460 (385-series) Big Block.

Ninety-nine percent of the time the term Big Block is superfluous. If someone says “This Coronet has a 383 Big Block,” they’re being truthful, but needlessly redundant. A 383 is a big engine, that’s what matters. And the people who care about such things, they already know.

Chevrolet 400 (6.6 litre) Turbo-Fire Small Block V8. Larger displacement than many Big Blocks.

The only time the distinction needs to be made is in the case of Chevrolet’s “400” V8. From 1970-1972, Chevrolet offered 400 cubic-inch V8s in both Small and Big-Block form. The Caprice for example, came standard with a 170hp Small-Block 400 cubic-inch V8, while a 210hp Big Block 400 was optional. Although the Big Block 400 was marketed as a “400,” it actually displaced 402 cubic-inches.

What about that Pontiac 455 not being a Big Block??? That’s right, the 455 was not a Big Block because Pontiac never had a Big Block. Or a Small Block. Throughout it’s entire existence, Pontiac only ever created a single V8 engine!

Pontiac 389 Tri-Power Trophy V8.

By varying the bore and stroke, Pontiac offered their sole V8 “Uniblock” in sizes ranging from 265 to 455 cubic inches, the most notable being the 326, 389, 400, 421 and 455.

1 thought on “Is That a Big Block Under the Hood?

  1. Well said.

    I’m old and a Mechanic and I hear ‘!big block!’ to describe Chevy 350’s made into stroker 383’s. Good engines to be sure but not big blocks.


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