If you were to say the words “350 small-block”, any automotive enthusiast worth their salt would automatically respond by jumping headlong into a discussion of famed Chevrolet powerplants. Chevrolet and the 350 cubic-inch V8 go together like pancakes and syrup, carrying a long history that dates back more than 50 years.
The 350ci V8 was actually a further extension of GM’s decade-old small-block engine series. In a bid to further cement the Corvette’s performance legacy, subsequent modifications to these earlier engines were made, thereby giving birth to one of General Motors’ most illustrious engine platforms. This platform, in itself, would serve as a mainstay of the Corvette line for over three decades to come.
350 Cubic-Inch Small Block History
During the earliest days of the Corvette’s initial production run, America’s sports car was regularly ridiculed for being underpowered at most every turn. This was especially concerning, as the 1950s were a time when many automotive manufacturers began to dramatically increase their performance standards.
Finally in 1955, after two years of production, the Corvette was offered with an optional small-block V8 powerplant. This initial 265ci “Mighty Mouse” small-block was rated to produce 195 horsepower, which was relatively impressive for the era in which it was produced. This also served as a vast improvement over the Corvette’s prior 150 horsepower “Blue-Flame” inline-six engine.
Over the next decade, GM’s 265ci small-block would be revised on numerous occasions. In 1957, the small-block’s displacement would be increased to 283 cubic inches, thereby bolstering the engine’s output to an impressive 245 horsepower when paired with two four-barrel carburetors. Consumers could also pair the 283ci with an optional “Ramjet” fuel injection system, which would bring the engine’s total output to 259 horsepower.
Further revision again increased the small-block V8’s displacement, this time to 327 cubic-inches. The 327ci V8 produced 350 HP and 358 lb-ft of torque when equipped with GM’s Rochester fuel injection system.
Then, in 1969, the GM 327ci V8 was stroked to 3.48-inches, thereby increasing the engine’s displacement to 350 cubic inches. GM offered this engine in two different formats, for the Corvette during the 1969 model year, a 300 HP version, and a larger 350 HP variant.
GM would continue offering the 350ci V8 for fitment into production models, for more than 30 years. Ultimately, this engine would go on to heavily influence key design points and architecture of the hugely popular LS engine platform to come.
350CI Small-Block Specifications and Technical Configurations
The 350CI small-block V8 served as a hotter version of the 327CI before it. This small block featured a cast-iron block, which included thicker bulkheads and more substantialized main bearing caps. All L46 350CI small-blocks were also of a four-bolt construction. Additionally, a forged crankshaft and pistons were also used.
The L46 featured cylinder bore diameters of 4.00-inches (101.6mm), and a 3.46-inch (87.88mm) stroke. A compression ratio of 11.0:1 was also standard fare for the famed L46 350 cubic-inch small-block V8.
Unlike many GM small-blocks before it, the L46 featured a hydraulic lifter camshaft, as opposed to a solid lifter alternative. This eliminated the need for guide plates, such as those that are necessitated in solid lifter engines.
The L46 featured a set of cast-iron cylinder heads, which were fitted with 2.02” intake valves, and 1.60” exhaust valves. Ironically, these are the same valves featured in GM’s L82 and LT-1 powerplants.
Atop the L46’s heads sat a low-rise cast-iron intake manifold. This intake was said to have been designed in this manner to provide ideal fitment beneath the C3 Corvette’s low-lying hood. Unlike many prior GM small-blocks, the L46 did not feature a Holley carburetor. Instead, a Rochester Q-Jet carburetor came standard.
All things considered, the 350 cubic-inch L46 produced 350 HP at 5,600 RPM, and 380 lb-ft of torque at 3,600 RPM.
350CI Specs Index
- Horsepower: 350 hp @ 5,600 RPM
- Torque: 380 lb./ft. @ 3,600 RPM
- Compression Ratio: 11.0:1
- Displacement: 350 cubic-inches (5.7 L)
- Cylinder Bore: 4.00 inches (101.6 mm)
- Stroke: 3.46 inches (87.88 mm)
Vehicles Using the L46
The L46 V8 is known primarily for its use in the Corvette, where it was presented as one of several engine options during 1969 and 1970. Variants of the L46 were also found in the Camaro during the late 1960s, most notably the L48. GM’s 350 cubic-inch small-block platform, as a whole, continued into the earliest years of the new millennium, before ultimately being discontinued.
A Chapter In A Much Larger Saga
While the L46 350 cubic-inch V8 is not often recalled as one of the most prestigious Corvette powerplants to have ever been produced, it did eventually give rise to numerous classic Corvette engines in the years and decades that followed. In fact, the 1970s LT-1 V8, which is often remembered as one of the Corvette’s most revered engine offerings, was based closely upon the L46’s design, even sharing many of the earlier engine’s components.
Perhaps of even greater importance, is the role that was played by the L46 in the illustrious history of GM’s 350 cubic-inch small-block platform. Engines of this make would remain in continual production up until 2003, serving as one of the manufacturer’s most iconic under-hood offerings.
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A few mistakes regarding the 327. With FI, it had 360 HP in 1963 and 375 HP in 1964 and 1965. The 283 FI in 1957 had either 250 HP or 283 HP.
The 1969 Chevy parts books included an over the counter 1969 LT-1 350 parts engine, which was the 1969 L-46 350 engine with the Z-28 302 intake and carb and an over the counter 1969 Z-28 302, “improved torque” camshaft, that turned out to be the production LT-1 camshaft. The 1969 over the counter LT-1 engine would differ from the 1970 production engine by not having the push rod guide plates and hardened push rods the 1970 engine had. Even some maintenance manuals include tuning for a, “1969” LT-1 350 engine.
Hi , I have a 350 lt1 with block number ending in HN 300 hp 4 bolt is it worth anything ?
I took possession of a 1969 350 LT-1 that had been sitting in the back corner of my uncle’s garage where he put it in 1969 after pulling it from my aunt’s Vett and replacing it with a V6 from a GMC truck to slow her down. well after going over it, This is what I found. it’s all stock from what I was told from the dealer that made the sail and delivery. Dave Burk of Burk motor’s Chevrolet, N.J. the short list is this; 760 C.F.M. Hollie double pump carburetor, excel dual point ignition, 30/30 cam on top of 10.5:1 piston’s. I had to pull it apart because it was stuck. I know that car had less then 1,500 on it when it was de-tuned so ta speak. and several older Grease’s informed me thatthis was a true race it on Sunday sell it on Monday factory rig because the rest of the production line was missing 100h.p. so I’m going to say 425H.P? one of Chevy’s unadvertised secrets for beating the competition??? perhaps.. I’m planning on returning it to its original form and putting it in my 1990 S-10 Street Gasser. (it will be replacing a 454RAT.) any offer close to $5,grand will take the Rat motor. less the carburetor. have fun with yourselves…