The introduction by Cadillac and Oldsmobile of overhead valve V8s in 1949 set off a wave of V8 fever that swept through the U.S. auto industry, starting with the premium brands and working its way down. Pontiac and Chevrolet were the last of GM's divisions to get their versions in 1955. The Chevy 265 had the smallest displacement and was the most compact of The General's group of new V8s, but it had the internal room to reach 350 ci in 1967. Just nine years earlier, the little V8 was thought to be close to maxed out with 283 ci and was joined in production by Chevy's first big-block, the 348ci W-engine (best known as the 409), 2 ci smaller than the 350ci small-block. Fifty years ago, there were doubts about the Gen I 350's long-term durability, but in the 1970s and 1980s, it became Chevrolet's most popular and widely produced V8, powering everything from Corvettes to pickups, and staying in production for 24 years.

The 265's block was considered to have a thin-wall casting in 1955, but its cylinder walls were thick enough to be bored from 3.75 to 3.87 inches for the 1957 model year. This increased displacement to 283 ci using the same 3.00-inch-stroke crank. With 4.40 inches between cylinder-bore centers and a 9.00-inch-block deck height, there was still room for expansion, and studies looking into increasing the small-block's displacement continued. Ed Cole oversaw the V8's design as Chevrolet's chief engineer and stayed involved with its development after being appointed general manager in 1956. Ed made sure the small-block's bore-to-stroke ratio stayed well under square, telling the engine group in 1957, "I want a 4-inch bore in that engine," though it wasn't possible at the time. Core shifts would have led to some cylinder walls being cast too thin and increasing oil consumption, but foundry methods were improving. By 1961, casting 4-inch cylinder bores on 4.40-inch centers was possible. Problems with core placement were eventually worked out by the foundry at Chevrolet's Tonawanda engine plant. The 4-inch-bore block entered production in 1962 with a crankshaft stroked from 3 to 3.25 inches, increasing displacement to 327 ci. The 283's 2.30-inch main- and 2-inch rod-bearing journals carried over along with the 2-bolt main bearing caps. Bearing problems showed up when Zora Arkus-Duntov's group hot rodded the 327 for the Corvette with hot solid-lifter cams, high-compression heads, and Holley four-barrels for fuel injection blowing out bottom ends. It took Chevrolet a lot of experimentation to find a material to hold up in the overloaded bearing shells, but once it did, the 327 became the high-water mark of Gen I small-block performance, with the 1964 and 1965 fuel-injected L84 producing 375 hp.

Chevrolet rapidly expanded its product lineup with the compact Chevy II in 1962, followed by the midsized Chevelle in 1964. Chevrolet's answer to Ford's Mustang, the Camaro, was in the works when the 396ci MK IV big-block came out in 1965. With the 396 eventually available in all of these cars and a 427ci version coming out for the Corvette and fullsized sedans in 1966, there wasn't a single high-performance, solid-lifter small-block on any option list that year. Excluding the Flat 6 in the Corvair, a 283 or 327 was the base V8 in all of Chevy's products, and though Cole was promoted to group vice president in 1961, he was involved in negotiating still more cubic inches into the small-block. Cole's instructions were, "I want 350 cubic inches, and I want it all in the bore," which was a challenge to Chevy's engineers to keep the stroke as short as possible, because it couldn't be done otherwise.

The small-block's bore centers were too close together for pistons with a large enough diameter to increase its displacement to 350 ci but maintain the 327's 3.25-inch stroke, even if they rubbed together without cylinder walls in between. This meant staying with the 4-inch bore and increasing the stroke to 3.48 inches, which was a squeeze in a crankcase designed for 3 inches. Cole got his 23 ci, but it was all in the stroke. The project was assigned to Mystery Motor designer Dick Keinath's production V8 engineering group, starting an ongoing argument over whether they could successfully get that much displacement and get it to live. Fortunately, the 350 was intended to be a passenger-car engine for everyday transportation, and it promised to have good, long-term durability in that role as long as it wasn't hot rodded. However, it didn't work out that way, and Dick was horrified to find that the long-stroke small-block would debut in the 1967 Camaro SS 350.

The 350 was a Camaro exclusive in 1967, and Keinath's guys played it safe with a Rochester Quadrajet four-barrel sitting on a cast-iron intake manifold (sourced from the 275hp 327) under its high-performance chrome air cleaner. The 1.94-inch intake and 1.50-inch exhaust small-valve heads holding up chrome valve covers were also shared with the 275hp 327, and its hydraulic lifter cam was even used in the 195hp 283. These underwhelming parts ensured the 3.48-inch-stroke crank wouldn't be over-stressed while benefitting from the small-block's first increase in bearing diameters with 2.10-inch rod- and 2.45-inch main-bearing journals still running two-bolt caps. In addition, the connecting rods were beefed up, adding both reciprocating and rotating weight requiring larger crankshaft counterweights and necessitating raising the bottoms of the cylinder bores and modifying the pan rails for clearance. With flat-top, cast-aluminum pistons and 63cc combustion chambers, the 1967 350ci L48 had a 10.25:1 compression ratio and produced 295 hp at 4,800 rpm with 380 lb-ft of torque at 3,200 rpm; it was, essentially, a 327ci L30 with 23 more cubic inches, adding 20 hp and 25 lb-ft of torque.

The SS 350's performance didn't live up to its sporty image, but its cautious introduction proved to be the right move, because there were early problems with a few production engines breaking off the nose of their crankshafts. The larger counterweights reduced the crank's frequency, making it vulnerable to torsional breakage, which happened even though it was a steel forging. The problem was quickly solved by press-fitting the torsional damper and adding a draw bolt to the nose, putting its fillet on the first crank throw under tension and allowing nodular, cast-iron crankshafts in 1968 without problems. The 350 was still rated at 295 hp in 1968, with the across-the-board installation of the A.I.R. emission-control system on all of Chevrolet's V8s and with the entire family of small-blocks getting larger-diameter 2.45-inch main- and 2.10-inch rod-bearing journals. Along with the Camaro, the L48 was available in the Chevy II Nova, with a 350 making it the "Chevy II Much." A 325hp, 327-powered Nova would probably have been too much for a Chevy II Much to take on.

In 1969, after two years of production of the 350, more horsepower could be ordered in all of Chevrolet's front-engine cars, including the Corvette, in both its base engine and with a high-performance option. There were now three versions, with a slightly more powerful 300hp L48 available in the Corvette, Camaro, Chevelle, Chevy II, and fullsized sedans. The high-compression, 350hp L46 was a Corvette exclusive—the only car in which the low-compression 255hp L65 wasn't available. Only the L65 had two-bolt main-bearing caps; both the L48 and L46 crankshafts were supported by four-bolt bearing caps. All three 350s shared a lot of parts, but many of them were no longer borrowed from other engines. Small-blocks were very responsive to hot rodding, and all it took for the L46 to pick up 50 additional horsepower was increasing its valve diameters from 1.941.50 to 2.021.60, raising its compression ratio from 10.25 to 11:1, and adding a more aggressive hydraulic-lifter cam. The L46 developed 350 hp at 5,600 rpm and 380 lb-ft of torque at 3,600 rpm, which equaled the 300hp L48's 380 lb-ft at 3,200 but offered 20 more horsepower than the 1968 Corvette's base 300hp 327 it replaced.

For the 1970 model year, a change in the Trans-Am rules allowing larger engines to be de-stroked to the series' 5.0L (305ci) displacement limit gave rise to a fourth 350 to Chevrolet's engine lineup. This road-racing series was started by the Sports Car Club of America in 1966 for ponycars like Ford's Mustang, and a 302ci small-block was added to the 1967 Camaro's option list midyear, allowing it to compete. The 302 used an updated version of the 283 3-inch-stroke crank in the 4-inch-bore 350-block machined for the small main bearings in 1967 as part of the Z28 racing package, but with manufacturers no longer required to offer 5L V8s, the 1970 Z28 came with a 350. This engine was designated LT1, and like the 302 it replaced, was Chevrolet's only solid-lifter small-block 350 to achieve legendary status during Detroit's first performance era.

The LT1, with its additional 48 ci was a more streetable 302, breathing through a four-barrel Holley on a Z28 cast-aluminum, high-rise intake manifold with the same 2.021.60 big valve heads dating back to the 1964 365375hp 327s. The solid-lifter 302 cam was also sourced and had the same .485 lift with 345 degrees of duration for both intake and exhaust. The LT1 cam was new with 0.4580.484 lift and a duration of 317346 degrees for intake and exhaust. The Z28 302 used the 350-block for all three years of production, and like the 350hp L46, the LT1 had a forged-steel 3.48-inch-stroke crank with four-bolt main-bearing caps. By 1969, small-block connecting rods were developed in five designs, with the Z28 using the forged-steel, shot-peened, heat-treated fourth design. Now there was a sixth option with the LT1 in 1970, offering additional valve lift and duration. As on the 350hp L46, LT1 pistons were forged aluminum with a pop up to increase the cast flat-top pistons' compression ratio from 10.25 to 11:1.

In the 1970 Z28 Camaro, the LT1 was rated at 360 hp at 6,000 rpm with 380 lb-ft of torque at 4,000 rpm, but installed in a Corvette, it was listed with 370 hp at 5,800 rpm and the same 380 lb-ft at 4,000 rpm. This was partly because the Corvette ram-horn exhaust manifolds were less restrictive than the Camaro's log-type design, but it was also about marketing, giving Chevy's premium performance car the more powerful engine. The LT1 missed the distinction of being Chevrolet's most powerful Gen I small-block by 5 hp, but it was the most powerful carbureted small-block and had a 28 lb-ft advantage in torque over the fuel-injected, 375hp, 327ci L84 that took the title. However, in 1970, the horsepower war was already over with President Nixon signing the National Environment Policy Act on New Year's Day, making high-performance production cars an endangered species, soon to be extinct.

The bill mandated a 90-percent reduction in pre-1968 exhaust emissions by 1975, without specifying how this seemingly impossible feat would be accomplished. But the industry and the Feds saw a catalytic muffler patented by Eugene Hourday in 1962 as the only solution. This device had a big downside, as the tetraethyl lead added to gasoline to improve detonation resistance would poison the catalyst, so lead was completely removed from the national fuel supply by 1975. Compression ratios had to fall, and with them horsepower, so with only 91-octane low-lead commonly available at gas pumps in 1971, the decompression of Chevrolet's engine lineup got underway, with ratios dropping to a low of 8:1. The 1971 LT1 fared a little better with a compression ratio of 9:1, leaving it with 330 hp. In 1972, with the industry now reporting SAE net instead of gross ratings, it went out of production with 255 advertised horsepower.

Chevrolet met the EPA's mandate with a much-reduced engine lineup of five small-block V8s—all but one being 350s—equipped with catalytic converters and certified to be in compliance with 1975 exhaust-emission regulations. The most anemic 1975 350 was rated at 140 hp with a two-barrel carburetor, while the Corvette's base version had 165 hp with a four-barrel. Vette buyers craving more power could order the 205hp L82 offering 210 hp in 1976. This rapid reduction in exhaust emissions came at the expense of fuel economy, and the EPA not only started requiring annual reductions in emissions but also improvements in gas mileage starting in 1976, leaving the industry playing catch up for the rest of the decade. By 1980, horsepower was slowly making a comeback with the Corvette's base 350 jumping to 190 hp from 165 in 1975, except in California. There, the only engine available in the corvette was a 180hp 305. The optional L82 gained 65 horses, bringing it up to 230 hp.

It would take electronic-port fuel injection with digital-engine management to bring back exciting performance, and Chevrolet started by adding "computer command control" to the Corvette's carbureted base 350, bringing it up to 190 hp. In 1982, "cross-fire fuel injection" replaced the carburetor with a pair of throttle-body fuel injectors on a cross-ram intake manifold, adding 10 more horsepower and better fuel economy and driveability. The fourth-generation Corvette was introduced with this engine in 1984, but in 1985 it was powered by the 350ci L98, bringing port fuel injection back to the Corvette after a 20-year absence. However, instead of Rochester's fussy mechanical system, this time it was electronic. The L98 had a cast-aluminum intake plenum suspended above its block valley on tuned-length tubular runners, and in 1985 and 1986, it produced 230 hp at 4,000 rpm and 330 lb-ft of torque at 3,200 rpm. By 1987, horsepower increased to 240 at 4,000 rpm and torque to 345 lb-ft at 3,200 rpm, which still doesn't sound all that impressive. But it was enough power to propel the slippery C4 to mid-14-second quarter-mile times with a top speed of more than 150 mph.

Making further gains in performance and deal with durability problems appearing after more than 30 years of small-block V8 production took rethinking the engine, leading to redesigning most of the major components. Introduced as a second coming of the 350ci LT1 in the 1992 Corvette, the Gen II small-block stayed with the original architecture, even though only a few parts were interchangeable, and it featured reverse-flow cooling. A geardriven water pump fed coolant into the heads first instead of the block for cooler heads and hotter cylinder bores, increasing both volumetric and thermal efficiency. The Gen II LT1 produced 300 hp at 4,800 rpm and 320 lb-ft of torque at 4,000, with a hot rodded version of the LT4 rated at 330 hp, available for the last of its brief, five-year production.

Rethinking the small-block V8 went beyond the Gen II. Investigating how the engine could reach 350 to 400 hp led to a new beginning, with only the original 4.40-inch-bore centers carrying over from 1955. The 1997 LS1 was still a central-cam, pushrod V8 but with an aluminum-block that extended below the crank centerline with four-bolt main-bearing caps cross-bolted through its side skirts and cast in iron cylinder liners reducing displacement to 346 ci. The heads were also cast aluminum with equally spaced ports. This replaced the earlier book-fold pattern that put the intake ports in two pairs with a single pair of exhaust ports centered between the two on the ends. The intake manifold was black nylon-6 plastic with individual ignition coils mounted on the valve covers above each spark plug, making the LS1's underhood appearance less impressive than the LT1 but with better numbers: 345 hp at 5,600 rpm and 350 lb-ft of torque.

In 2001, the LS1 picked up 5 hp, thanks to a new cylinder block, air cleaner, intake, and exhaust manifolds designed for the 385hp LS6 that was only available in the high-performance Z06 Corvette hardtop. The 2001 LS6 was a work in progress, with the 2002-and-later versions rated at 405 hp with 400 lb-ft of torque. That was the end of the line for production 350 horsepower development. Then the 364ci LS2 Gen IV for the C6 Corvette came out in 2005. The LS2 was the C6 base engine that produced 400 hp. The 2006 Z06 returned with the 427ci LS7, larger than the low-performance 400ci small-block produced from 1970 to 1974, rated at 265 gross hp compared with the LS7's 505 net horsepower. The Corvette's base engine got even bigger with the 376ci, 430hp LS3 in 2008, followed by the supercharged 638hp LS9 in 2009, sharing its displacement, as does today's 650hp supercharged Gen V LT4. All of these amazing engines have the 265 and 350 LS1's DNA.