Buick was long known for its big V8s with loads of torque, and the biggest of all arrived in 1970 with the  455.

The story of Buick’s 455 cubic-inch rightly begins with the GM division’s next-generation V8 introduced in 1967 (above) to replace the original Nailhead V8. (See our Nailhead feature here.)  Two displacements were originally offered: 400 and 430 cubic inches, and while the new V8 shared the same 4.75-inch bore spacing as the Nailhead, it was different in every other way.

In fact, this new V8’s basic architecture was much like that of the Buick 215 cubic-inch aluminum V8, only larger. (Meanwhile, the 215 evolved into a cast-iron 350 CID V8.) The distributor is at the front, while the timing cover, oil pump, and related hardware are essentially enlarged versions of the 215-to-350 design. However, there is nothing petite about the big Buick V8’s  construction. It’s robust, as any Buick mechanic who’s handled the components can attest, though its total weight is less than 650 lbs fully dressed.

There’s an SAE paper (670083) by Buick assistant chief engineer Clifford G. Studaker that covers the engine in full detail, but here are a few of the more noteworthy features. The main bearings are a full.3.25 inches in diameter, in part to enable the use of a nodular iron crankshaft instead of the more costly forged crank of the Nailhead. (For scale, the Chrysler 426 hemi’s mains are 2.75 inches in diameter.)

Studaker also noted that special consideration was given to valve spacing and port configuration, areas that had limited the Nailhead’s displacement and output potential. Valve diameters were considerably larger than the Nailhead (2.00-in intake and 1.625-in exhaust) with room for growth, which would come in handy a few years later.

When the big V8 was enlarged to 455 cubic inches for 1970, the 3.90-in stroke of the 400 CID  and 430 CID engines was maintained, but the bores were opened up to 4.3215 inches, yielding a comfortable stroke/bore ratio of .904:1.There were no other significant changes but with the larger displacement, the base 455 with a four-barrel carburetor and a 10:1 compression ratio.developed 350 hp at 4,600 rpm. Better yet, it pumped out 510 lb-ft of torque at just 2,800 rpm—perfect for the big luxury cruisers with automatic transmissions that were Buick’s bread and butter.

But also in 1970, the engineers at the luxury division flipped the script and released the Stage 1 version of the 455 for the Gran Sport and GSX. With larger valves, a bump in compression ratio to 10.5:1, and a sportier camshaft, it was rated at a nominal 360 hp, but the number was sandbagged by a good 35 hp, Buick experts say. There was also a Stage 2 parts package with even more porential. In truth, the Stage 1 and Stage 2 V8s were among  the more potent engines of the muscle car era, and a story in themselves.

For 1971, the compression ratio was dropped to 8.5:1. and in 1972 the quoted output for the base 455 was dropped to 250 hp as GM shifted to the SAE net rating system. As Buick engineers struggled to meet emissions requirements, by 1975 the output dropped to only 205 hp, and 1976 proved to be the final year for the 455. Buick’s B-body and C-body full-size cars were being downsized for 1977, and there was no longer a need for a large-displacement V8.