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. The 1970 500 cubic-inch, 8.2-litre Cadillac V8 was a big engine (indeed a rather massive 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 were big blocks, but a Pontiac 455 was 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. Incanting the term Big Block wasn’t meant to summon ancient mystical powers, it was simply to indicate that an engine in question was built using the larger of two available block castings.

As engines grew in displacement, small block families expanded to the extent that displacement overlap with big blocks started occurring. This first began in 1967 when Chevrolet introduced a 350 cubic-inch version of its small block V8, two cubic-inches larger than their original 348 big block motor.

Hence, displacement is not directly correlated with block size. A 400 cubic-inch Chevrolet Turbo-Fire V8, larger in displacement than a Chevrolet 396 big block, was in fact a bored and stroked small block. A big engine by any standard, but 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: 287, 327 (applicable beginning in the spring of 1966 when the AMC small block 290 was introduced)

Buick: 364 (applicable from 1961 when Buick small-blocks were first introduced), 400, 401, 425, 430, 455

Chevrolet: 348, 396, 402 (marketed as a 400), 409, 427, 454

FoMoCo: 332, 352, 361, 368, 383, 390, 406, 410, 427, 428, 429, 430, 460

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

Oldsmobile: 371, 394, 400, 425, 455

Sharp-eyed readers might notice that I left out the Ford 462. That was a Lincoln-only power plant; and since Lincoln offered no smaller alternative, the term big block would be (as it so often is) gratuitous. As to Cadillac, they never offered multiple displacements (much less small and big blocks) until 1970 when the 500 was introduced alongside the 472. The new 500 was simply a 472 block with identical bore diameter and a longer-stroke crankshaft.

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. “383 tells us the displacement, that’s what matters. And the people who care about such things, they already know that a 383 is a Mopar big block.

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 engines in both small and big block form. The 1971 Caprice for example, came standard with a 255 hp small block Turbo-Fire 400 V8, while a 300 hp big block Turbo-Jet 400 (actual displacement 402) was optional.

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 its entire existence, Pontiac only ever manufactured a single V8 engine family!

Pontiac 389 Tri-Power Trophy V8.

By varying bore, stroke, journal size and deck height, Pontiac offered their sole V8 Uniblock in displacements ranging from 265 to 455 cubic inches, the most renowned being the 326, 389, 400, 421, 428 and 455.

Bear in mind that a big block is not necessarily a one-size-fits-all holy grail. They were designed to power big, heavy cars; and they too were big and heavy, often over one hundred pounds more corpulent than a small-block. When shoehorned into the nose of a smaller car like a Camaro, Mustang or Corvette, they can be a significant detriment to the handling agility and control responsiveness prized by the discerning driver.

In 1966, eminent musicians and car enthusiasts Brian Wilson (co-writer of 409, Dead Man’s Curve and Drag City) and Jan Berry (co-author of Dead Man’s Curve, Drag City and Little Old Lady from Pasadena), either of whom could have written a cheque for a warehouse full of big-blocks, both bought new Sting Rays powered by the 327 small-block.

Brian Wilson with his Sunfire Yellow
1966 Sting Ray 327 Convertible

A few months later, Car and Driver magazine stated their own preference for the 327 Corvette finding it “lighter, better balanced, and more responsive than the 427.” Car and Driver would eventually give the 427 their imprimatur, but only after optional aluminum cylinder heads became available for 1967, slashing the big block’s weight penalty from a rather substantial 118 lbs. (54 kg) to only 40 lbs (18 kg).

3 thoughts 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.


  2. I believe the Chevy 402 was marketed as a 396 as SS 396 was a performance option with a ring to it. So when the motor increased to 402 cu. In. They still referred to it as a 396. The 400 was a “siamese” bore and possibly longer stroked version of the 350 small block.

    • Yes indeed; when it debuted in 1970 the new 402 was marketed as a “400” in the full-size cars and pickups, but continued to be sold as a “396” in Chevelles, Novas and El Caminos. Chevrolet realized that the 396 had substantial brand equity among performance enthusiasts and decided to leave the name unchanged even though in the case of the Chevelle SS 396, it was now eclipsed by the new SS 454.

      The 400 did have a longer stroke crank than the 350: 3.75″ vs. 3.48.”

Comments are closed.