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The Chevrolet 327 Engine

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65 chevelle engine

The 327-cubic-inch Mighty Mouse

The Chevrolet 327-cubic-inch V8 originated with the small-block family of engines that first appeared in 1955 with a 265 cubic inch powerplant. Following with a 283 cubic inch version that appeared in 1957, the mighty 327-inch small block made its debut in 1962. Although the 327 was eventually superseded by the 350 across the entire Chevrolet product line, the intermediate displacement 327 was used in just about every Chevy on the market between 1962 and 1969, including the Malibu, Impala, El Camino, Chevelle, Chevy II and Corvette.

During its eight years of production, the potent 327 engine became known among small-block aficionados as a “mighty mouse” of a motor that was extremely compact and efficient. The high efficiency came from the fact that the 327 block’s large cylinder wall castings allowed four inch bores that could utilize large valve heads. The engine also had a relatively short 3.25-inch stroke that yielded a 1.75:1 rod to stroke ratio when fitted with the standard small-block 5.7-inch small-block rods. This meant the 327 came very close to the “near perfect” 18:1 rod/stroke ratio that many engine builders of the day claimed was the best for building a fast-revving engine. Even with the installation of longer aftermarket rods, the 327 design did not need odd-shaped, compromise design pistons that later, longer stroke engines often required. The 327 worked very well with the carburetors, pistons, cylinder heads, intake manifolds and camshaft used that were available in the late 60’s, and its big horsepower-per-cubic-inch potential made it a favorite among enthusiasts for both the street and strip.

In 1962, the 327 was offered in four different power ratings depending on the vehicle it was in. The base models produced through 1965 with four-barrel carburetors and a 10.5-to-1 compression ratio made 250 horsepower and 350 foot pounds of torque. Another version manufactured through 1968 featured a four-barrel carburetor and the same compression ratio, but produced 300 horsepower and 360 foot pounds of torque. The “performance” model of the 327 at the time also used a four-barrel carburetor, but bumped the compression up to 11.25 to 1 to produce 340 horsepower and 344 foot pounds of torque.

Although most examples of the 327 were carbureted, some of the early Corvettes came equipped with fuel injection and made more horsepower. Thanks to Rochester fuel-injection and 1.94/1.50-inch valves, the 1962 and 1963 Corvettes claimed 375 horsepower. In 1964 and 1965, the Corvettes used the same heads with even larger intake valves (2.02 inches) to make 365 horsepower with a Holley carburetor or 375 horsepower with the Rochester fuel injection. The fuel injection, big valves and a 1-to-:1 compression ratio allowed the Corvettes to run the quarter mile in just under 15 seconds and zero-to 60 times were recorded at under 6 seconds. Those early 375 horsepower models were the fastest factory 327’s ever produced and by 1966 the engine dropped to 325 and 350 horsepower models that came with an 11-to-1 compression ratio. Factory interest and development of the 327 began to slow by 1966 when Chevrolet introduced the big-block 396 and 427. In 1967, the factory dropped the compression ratio of the 327 to a mild 8.5-to-1, and the power ratings began to fade with just 210 horsepower and 320 foot pounds of torque.

The last iteration of the 327 appeared in 1969 with a two-barrel carburetor and a 9-to-1 compression ratio that produced 235 horsepower and 325 foot pounds of torque, but by then another Chevrolet small-block had already appeared on the market and had begun stealing what thunder the 327 had left. Prior to the appearance of the larger and ultimately more versatile 350 cubic-inch small-block Chevrolet in 1967, the compact 327 was the most powerful and most efficient small-block engine Chevrolet had ever produced. That the 327 is still utilized by many classic Chevrolet fans today is testament to its lasting legacy of power and efficiency.

Browse our selection of Restoration and Performance parts for the Chevy 327 Engine below.

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