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
The Chevrolet small-block engine is a series of gasoline-powered, V-8 automobile engines, produced by the Chevrolet division of General Motors between 1954 and 2003, using the same basic engine block.
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Despite being down on inches to the 350, the 327 Chevy still lays claim to the most powerful production conventional small-block ever produced, the L84. Rated at 375 hp, the fuel-injected 327 was a high-winding screamer, as satisfying to drive as any big-block.
The 327 was a mainstay of Chevrolet's engine lineup from 1962 through 1969, when it made its final appearance as the standard V-8 in that year's fullsize Chevys, and as a low-cost option over the base 307-inch V8 in the Chevelle, Nova and Camaro.
Hagerty calls the 327 a “power-packed small-block,” and the Original Parts Group dubs the power plant “potent.” The folks at the popular auto blog On All Cylinders include the 327 in the No. 3 slot on its list of the “Top 5 Small Block Chevy Engines of All Time.” These are impressive accolades, of course.
The larger sized main journal diameters of the 1968 327 small-block, 2.450, are the exact size of the later 350 small-block. The difference between the two is the length of stroke on the crank, 3.250 for the 327 and 3.484 for the 350.
The L74, 300hp 327s Chevy IIs totaled 319. Few knew these two 327 RPOs even existed. Both are ultra rare today. Either of these 327 engines in the Chevy II, Chevelle and big car could be had with an automatic or manual transmission-three- or four-speed.
The largest-displacement small-blocks ever produced by GM are the LSX454/LSX454R crate engines offered through Chevrolet Performance, at 454 cubic inches (7.4L); the largest-displacement small-block for a production vehicle is the 427-cubic-inch (7.0L) LS7 used currently in the Corvette Z06.
The bottom end of a stock 327 can be safely spun up to 6500 RPM if it is in good shape. A stock 327 with power pack heads and a stock cam will run out of breath above 5000 RPM. The power pack heads have small valves (1.72 intake &1. 50 exhaust), and a stock cam is designed to make power below 4500 RPM.
Although the 327 was eventually superseded by the 350 across the entire Chevrolet product line, the intermediate displacement 327 was used in just about every Chevy on the market between 1962 and 1969,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.
Chevrolet never used a 4 bolt main 327 in there production cars, but sounds like there might be some out there in industrial versions according to silvercab. They did make 4 bolt main 350s, and in '69 the 302 had 4 bolt mains. Consequentially, the 302, 327, and 350 all had a 4" bore.
Displacement: Big block engines tend to have displacements of 400 cubic inches or more. There are exceptions to this rule, such as the Chevy 396 engine which is referred to as a big block engine due to its architecture.
The L76—like its LS2 sibling—is a 6.0L, Gen. 4, aluminum small block engine that was used both in GM cars and trucks. The L76 is an adapted version of the LS2, featuring new rectangle port cylinder heads and Active Fuel Management (AFM). The L76 was available in the Pontiac G8 GT from 2007-09.
The 350 is 4.00" by 3.48". There is such a thing as a 350 big block, but it is NOT a Chevy. Pontiac, Olds and Buick each made a 350 and all three are considered big blocks (same blocks as their respective 400 and 455 engines).