Introduction
The Chevrolet 350 engine, commonly referred to as the "Chevy 350" or the "Small Block V8 350," is a 350‑cubic‑inch (5.7‑liter) internal‑combustion V8 engine that was first produced by the General Motors subsidiary Chevrolet in the mid‑1960s. The engine was developed as part of Chevrolet’s effort to replace the aging 283 and 327 engines while providing a more powerful, efficient, and affordable powerplant for a wide range of vehicles. Over its production lifespan, the 350 has become one of the most recognizable and widely used engines in the automotive industry, thanks to its robust design, reliability, and the extensive aftermarket support that has grown around it.
Although the original 350 was initially designed for passenger cars and light trucks, its adaptability has led to its use in performance applications, racing, marine propulsion, and even some heavy‑duty industrial equipment. The engine’s long service life, combined with its straightforward construction, has made it a popular choice for engine swaps, restorations, and modifications. This article surveys the development history, design characteristics, technical specifications, variants, applications, and legacy of the Chevy 350 engine.
History and Background
Genesis of the Small Block Program
In the early 1960s, General Motors began a comprehensive effort to unify and modernize its small‑block V8 engines. The existing 283, 327, and 283‑B engines were derived from the 292 and 409 families but were increasingly seen as outdated due to limitations in performance and efficiency. Chevrolet’s engineering team, led by chief engineer Bill "Pope" McGonigle, sought to create a new generation of small‑block engines that could be shared across the GM brand, reduce manufacturing costs, and meet evolving emission regulations.
In 1964, GM announced the Small Block V8 family, consisting of the 265, 283, and later the 350. The 350 was introduced for the 1965 model year as the most powerful option in the family. The new engine maintained the 90‑inch bore spacing and 5.08‑inch stroke used in the previous generation but employed a more modern cylinder head design, improved fuel injection capabilities, and a redesigned camshaft profile that enhanced power output without sacrificing durability.
Development and Introduction (1964–1965)
The design process for the 350 involved a significant shift toward modularity. Key components such as the block, heads, and pistons were standardized across all Small Block variants, allowing for economies of scale. The new engine featured a single camshaft with a “bump” in the valve timing, providing a smoother transition between high‑performance and low‑speed operation. This design was also known as the "cam bump" and contributed to a more even power delivery.
Upon its introduction, the 350 was offered in several configurations: a naturally aspirated version for the Corvair and early Impala, a “High‑Performance” version for the Camaro and Nova, and a “Power Pack” version that incorporated a high‑lift camshaft and larger valves for improved airflow. The initial output of the naturally aspirated 350 ranged from 215 to 230 horsepower, while the high‑performance variants achieved up to 250 horsepower, depending on the application and tuning.
The introduction of the 350 coincided with the introduction of the 1970 Chevrolet Camaro Z28, which used a 350 engine with a high‑lift camshaft and a 4.4‑inch intake manifold. This engine produced 280 horsepower and set a new standard for performance V8s in the mid‑1970s. The Camaro Z28’s success cemented the 350’s reputation as a high‑performance powerplant.
Evolution Through the Decades (1970–2000)
During the 1970s, the 350 engine was adapted to meet stricter emission and fuel‑efficiency regulations. In 1974, the introduction of the “Super Power Pack” and “High Power Pack” engines in the Camaro and Nova series incorporated revised valve timing, higher lift cams, and improved camshafts. The engine also saw the introduction of a 90‑inch head bolt pattern and the use of a new, more robust oil pump to handle increased demands.
In the 1980s, the 350 was largely phased out in passenger cars in favor of the 4.3‑liter “Quad‑V” and the 5.0‑liter “T‑30” engines. However, it continued to be used in light trucks, commercial vehicles, and as a basis for aftermarket modifications. The 350’s block and head designs were also adapted for use in the 5.7‑liter (350 cubic inch) versions that featured a larger bore (4.1 inches) and the same stroke (3.75 inches), increasing displacement to 351 cubic inches. These versions were introduced in 1975 for the Chevrolet C‑30 truck and later became common in the Silverado and Tahoe.
The early 1990s saw the 350’s continued popularity in the aftermarket due to its straightforward mechanics and the availability of aftermarket components. Many engine builders began converting the 350 to fuel injection systems, higher‑lift cams, and performance heads to achieve significant power gains. The 350’s durability and simple architecture made it a favorite for engines that required high torque output for towing and hauling.
By the early 2000s, the 350 had been largely replaced in new production vehicles by the 5.3‑liter “L‑S” and 6.2‑liter “L‑S” engines. Nevertheless, the 350 remained in production for certain commercial vehicles, such as the Chevrolet Silverado 1500 and Tahoe, until 2005. After that, the engine’s production ceased, but its legacy continued through the widespread use of its components in other engines and the vibrant aftermarket ecosystem that still exists.
Design and Development
Block Construction
The 350 block is a cast‑iron construction that adheres to the 90‑inch bore spacing and 5.08‑inch stroke typical of the Small Block V8 family. The block features a crosshair pattern of coolant passages, a robust oil pan with a dual-branch oiling system, and a 4‑cylinder cylinder head attachment system. The engine block uses a 6‑pin design for connecting rods, which was later upgraded to 8 pins in the 1975 variant to improve strength and reduce weight.
Key aspects of the block design include a raised deck for improved cylinder head clearance, a reinforced crankcase shell, and an integrated oil pump that is driven directly from the camshaft. The use of an oil pump driven by a timing belt instead of a gear system allows for smoother operation and reduced noise. The block also features a unique valve spring return system that incorporates a spring return spring and a valve guide that helps maintain valve seating under high pressure.
The 350’s cast‑iron construction provides a balance between durability and weight, allowing the engine to produce high torque levels while maintaining structural integrity over long periods. The use of a reinforced deck and crosshair cooling system contributes to the engine’s reliability in heavy‑towing and high‑stress applications.
Cylinder Head Design
The 350 cylinder head is a two‑valve per cylinder cast‑iron design that employs a 3‑inch deck height and a 90‑inch head bolt pattern. The head uses a 1‑inch bore and 1‑inch head gasket pattern. It features a hemispherical combustion chamber that promotes efficient combustion and high compression ratios. The head’s valve arrangement uses a 24‑in‑long rocker arm for each cylinder, allowing for precise camshaft timing.
Valve timing on the 350 head is controlled by a single camshaft that drives both intake and exhaust valves through a pushrod system. The camshaft profile includes a “bump” to provide a smoother transition from low to high engine speeds. The use of a single camshaft simplifies the timing mechanism and reduces the number of moving parts, making the engine easier to maintain and repair.
The head also features a cast‑iron intake manifold with a 90‑inch head bolt pattern that can be replaced with aftermarket manifold designs to increase airflow. Many performance enthusiasts swap in “Rally” or “Performance” heads that have larger valves, improved port shapes, and upgraded combustion chambers for increased power output. The standard head’s design allows for a compression ratio range from 8.5:1 to 10.25:1, depending on the application.
Piston and Connecting Rod Configuration
The original 350 piston set is a 5‑inch flat‑head piston that offers a compression ratio range of 8.5:1 to 10.25:1. The piston skirt is designed with a 5‑inch length, providing a robust design that resists cracking and distortion under high torque loads. The piston rings are a standard set of a main seal ring, an oil ring, and a combustion seal ring, which provide efficient sealing and oil control.
The connecting rods used in the 350 are 5‑inch rods with a 2.5‑inch length. The rods are made from forged steel to provide high strength and resistance to fatigue. They incorporate a 4‑pin design for the crankshaft and a 6‑pin or 8‑pin design for the rod journals, depending on the variant. The use of a 4‑pin rod design reduces weight, but the 6‑pin design adds additional strength, allowing the engine to sustain higher horsepower levels without failure.
The piston and connecting rod combination is designed to provide a low center of gravity, reducing the engine’s overall weight and improving vehicle handling characteristics. The combination also allows the engine to maintain a high power density while ensuring a long service life.
Fuel and Ignition Systems
Early 350 engines were equipped with a mechanical fuel injection system that used a Bosch D-Jetronic injection system. Later variants switched to a mechanical distributor and a pushrod ignition system that used a magneto or a coil pack to generate spark. The ignition timing was controlled by a distributor that was set to a default timing of 8 to 12 degrees of crankshaft rotation before compression.
After the introduction of the 1974 “Super Power Pack,” many 350 engines were upgraded to a carbureted version with a single Holley or Carter carburetor. The carburetor was set to a 15:1 fuel to air ratio to provide optimal performance. Many 350 engines were later converted to fuel injection systems, either through the use of an aftermarket ECU or a GM “Tuned Fuel Injection” kit that allowed for more precise fuel metering.
The ignition system of the 350 uses a distributor or a coil pack that sends a high voltage spark to the spark plugs. The spark plugs used are standard 14‑mm spark plugs with a 10,000‑hour life. The ignition system also features an idle control valve that allows the engine to maintain a stable idle speed during low engine speeds.
Technical Specifications
General Specifications
- Bore: 4.1 inches (104.14 mm)
- Stroke: 3.75 inches (95.25 mm)
- Displacement: 351 cubic inches (5.7 liters)
- Compression Ratio: 8.5:1 – 10.25:1
- Power Output: 165 – 350 horsepower (varies by variant)
- Torque Output: 250 – 410 lb‑ft (varies by variant)
- Weight: 560–600 pounds (approx.)
- Cooling System: Water‑cooled, front‑mounted radiator
- Oil System: 5‑quart capacity, dry sump or wet sump options
- Valvetrain: Single camshaft, 4‑stroke, 32 valves (8 per head)
- Crankshaft: 8‑pin design for increased strength
Fuel System Variants
- Mechanical Fuel Injection (Bosch D‑Jetronic)
- Carbureted – Single Holley or Carter carburetor
- Electronic Fuel Injection (EFI) – Aftermarket conversion
Ignition Variants
- Distributor–based ignition system
- Coil‑pack ignition system (modern GM design)
- EFI–based ignition (aftermarket conversion)
Production History
Initial Production (1964–1967)
The 350 engine was first manufactured at GM's Bowling Green Engine Plant in Kentucky. Production began in 1964 for the 1965 model year and was aimed at the performance and luxury segments of the Chevrolet lineup. The first year’s production volume was approximately 20,000 units. The engine quickly became a staple in many Chevrolet models, including the Camaro, Nova, Caprice, and Corvette.
Expansion and Global Production (1968–1985)
During the late 1960s and early 1970s, the 350 was produced in several GM plants worldwide, including the Pontiac Engine Plant in Michigan and the Westinghouse Engine Plant in Ohio. The expansion of production locations allowed Chevrolet to meet increasing demand in the United States and abroad. The engine was also manufactured in Canada at the Oshawa Engine Plant for export to the Canadian market and for use in models such as the Pontiac GTO and the Chevrolet Caprice.
Decline and Final Production (1986–2005)
The 350’s production was gradually phased out in the mid‑1980s as newer engine families were introduced. However, the engine remained in production for specific commercial vehicles, such as the Chevrolet Silverado 1500, Tahoe, and Suburban. Production ceased in 2005 when GM discontinued the small‑block family in favor of the newer Modular V8 engines. Despite the cessation of production, the engine’s design continued to influence later engines in the GM lineup.
Variants
High‑Performance Variants
The 350 was offered in high‑performance configurations for the Chevrolet Camaro Z28 and the Pontiac Firebird Trans Am. These variants used a high‑lift camshaft, increased valve lift, and a larger 4.4‑inch intake manifold, producing power outputs of 280 horsepower or more. The high‑performance camshafts were typically 2.4‑inch lift with a 4.5‑inch duration at 0.050‑inch lift. These engines were designed for track use and high‑speed road performance.
High‑Lift Camshaft Variants
The 350’s high‑lift camshaft was available in both 5.0‑inch and 5.4‑inch variants. The 5.0‑inch camshaft offered a more aggressive lift profile, providing higher torque at lower engine speeds. The 5.4‑inch camshaft had a more aggressive lift and duration, producing higher horsepower at the cost of increased engine wear. Both camshafts were widely used in aftermarket builds and racing applications.
High‑Compression Variants
The 350 engine was also offered in high‑compression variants for use in diesel conversions. The high‑compression heads used a compression ratio of 12:1 or higher, allowing the engine to produce more power in diesel conversions. The high‑compression variants were also used in the early 1970s for the Chevrolet C‑30 truck, which was a light‑truck application that required higher torque output.
Diesel Conversions
In the 1970s and 1980s, many enthusiasts converted the 350 engine to diesel using a Garrett or a K&N induction system and a GM diesel fuel injection system. The conversions required a high‑compression ratio and a high‑load camshaft to provide the engine with the necessary torque. Diesel conversions of the 350 were popular for off‑road use, including the use in RVs and light trucks.
Aftermarket Performance Variants
Many performance enthusiasts replaced the stock 350 head with a performance head, using a larger valve size and improved port shapes. Aftermarket head kits, such as the “Rally” or “Performance” head kits, were available in both high‑lift camshaft and high‑compression variants. These kits allowed the engine to produce higher power outputs, making the 350 a popular choice for high‑performance builds.
Applications
Commercial Vehicle Applications
The 350 engine was used in several commercial vehicles, such as the Chevrolet Suburban, the Chevrolet Tahoe, and the Chevrolet Silverado 1500. These vehicles required higher torque levels and were often used for towing. The engine’s low RPM torque output was used for towing applications, which is why the engine is still used in many commercial vehicles today. The engine’s robust construction makes it an ideal choice for commercial applications that require high torque output and low engine RPM.
Car Model Applications
The 350 engine was used in the Chevrolet Camaro, Pontiac Firebird, Pontiac GTO, and the Chevrolet Caprice. These models required a high horsepower output and a low engine RPM. The engine’s high horsepower and low torque output made it a popular choice for high‑speed road performance. The engine was also used in the Corvette and the Corvette convertible, which required a high horsepower output and a high horsepower output at high engine speeds.
Track and Racing Applications
The 350 engine was used in track and racing applications such as the Chevrolet Camaro Z28 and the Pontiac Firebird Trans Am. These engines were specifically designed for track use and were often used in the early 1970s for racing events. The engines were also used in the early 1970s for the Chevrolet C‑30 truck, which was a light‑truck application that required higher torque output.
Military and Naval Applications
The 350 engine was also used in the US Army’s 1992 M777 howitzer. The engine’s low RPM torque output was used for the howitzer’s artillery fire. The engine’s low RPM torque output was also used for the US Navy’s 3‑tonne light‑ship. The engine’s low RPM torque output was used for the naval and marine applications, which required low torque output and high reliability. The engine’s low RPM torque output was also used in the US Navy’s 3‑tonne light‑ship.
Notable Uses
Performance Car Models
The 350 engine has been used in several performance car models, including the Chevrolet Camaro Z28, the Pontiac Firebird Trans Am, and the Chevrolet Caprice. The engine was also used in the early 1970s for the Chevrolet Caprice, which was a performance car that required high horsepower and high torque. The 350’s high‑lift camshaft was also used in the early 1970s for the 1974 Trans Am and the 1975 Firebird.
Commercial Vehicle Models
The 350 engine was used in commercial vehicles such as the Chevrolet Suburban, Tahoe, and Suburban. The engine’s low RPM torque output was used in the early 1970s for the C‑30 truck, which was a light‑truck application that required higher torque output. The engine’s low RPM torque output was also used for the US Army’s 1992 M777 howitzer. The 350 engine’s low RPM torque output was used in the US Army’s 1992 M777 howitzer.
Racing and Track Use
The 350 engine was used extensively in racing applications such as the Pontiac Firebird Trans Am and the Chevrolet Camaro Z28. The engine’s high‑lift camshaft and high‑compression ratio were used in many racing applications, including the early 1970s for the 1973 Trans Am and the 1974 Firebird. The engine’s high‑lift camshaft and high‑compression ratio were used in many racing applications.
Legacy and Influence
Influence on Subsequent V8 Engines
The 350 engine’s design has influenced many later engines in GM’s lineup. The use of a low‑center‑of‑gravity design, a reinforced deck, and a 1‑inch intake manifold has allowed many modern engines to benefit from the design’s high torque and low rpm. Many modern GM engines, such as the Modular V8 family, incorporate some of the design features found in the 350.
Modern Performance and Racing Applications
The 350 is still used in many modern performance and racing applications. Aftermarket modifications allow the engine to be tuned for high horsepower and torque. Many performance enthusiasts use the 350 for a variety of builds, including the V8‑based 1970s Corvette and the 1976 Camaro Z28. The engine’s ability to produce high torque at low engine speeds makes it ideal for track racing and high‑speed road performance.
Conclusion
The Chevrolet 350 engine has been a staple of GM’s performance and commercial lines since the 1960s. Its design and performance characteristics have made it one of the most popular engines in automotive history. The engine’s legacy continues today, as many modern engines incorporate some of the design features found in the 350.
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