Hubbry Logo
Chrysler A engineChrysler A engineMain
Open search
Chrysler A engine
Community hub
Chrysler A engine
logo
8 pages, 0 posts
0 subscribers
Be the first to start a discussion here.
Be the first to start a discussion here.
Chrysler A engine
Chrysler A engine
Chrysler A engine
View on Wikipedia
from Wikipedia
Chrysler A engine
Overview
ManufacturerChrysler
Also calledPlymouth A engine
Production1956-1961 Mound Road Engine, Detroit, MI
Layout
ConfigurationV8
Displacement
  • 276.1 cu in (4.5 L)
  • 299.6 cu in (4.9 L)
  • 302.5 cu in (5.0 L)
  • 312.5 cu in (5.1 L)
  • 317.6 cu in (5.2 L)
  • 325.2 cu in (5.3 L)
Cylinder bore
  • 3+3⁄4 in (95.2 mm; 3.75 in)
  • 3+13⁄16 in (96.8 mm; 3.81 in)
  • 3+7⁄8 in (98.4 mm; 3.88 in)
  • 3+29⁄32 in (99.2 mm; 3.91 in)
  • 3+61⁄64 in (100 mm; 3.95 in)
Piston stroke
  • 3+1⁄8 in (79.4 mm; 3.13 in)
  • 3+5⁄16 in (84.1 mm; 3.31 in)
Cylinder block materialCast iron
Cylinder head materialCast iron
ValvetrainOHV 2 valves x cyl.
Combustion
Fuel system4-barrel Carburetor
Fuel typeGasoline
Oil systemWet sump
Cooling systemWater-cooled
Output
Power output187–290 bhp (139–216 kW)
Chronology
PredecessorPolyspheric engines
SuccessorChrysler LA engine

The Chrysler A engine is an OHV small-block V8 gasoline engine built by Chrysler from 1956 until 1967. It featured polyspherical combustion chambers, and was offered in displacements from 276.1 cu in (4.5 L) to 325.2 cu in (5.3 L), and in various high-power configurations. It began to be replaced by the wedge-head LA engine in 1964, and is not related to the hemispherical-head Hemi engine of the 1950s or 1960s.

The A engine was released in 1956, and was used exclusively in Plymouths until 1958 and in Chryslers and Dodges from 1959 on. The DeSoto and Dodge 270/315/325 poly used similar head architecture but was not related to the Plymouth A Engine, using its own heads and the same bottom end as the Dodge and Desoto Red Ram Hemi. The A engine cylinder bore center distance is 4.46 in (113.3 mm), larger than the earlier Dodge-based poly engines. The A engine formed the design basis of the Chrysler LA engine, evidenced in the many parts that interchange between the two engine families.[1]

Plymouth

[edit]

277

[edit]

The 277 "Hy-Fire" was the first A-block engine, produced for 1955 in the fall of 1954 and sharing almost nothing but the basic concepts with other engines built by Chrysler. Bore is 3+3⁄4 in (95.3 mm) and stroke is 3+1⁄8 in (79.4 mm; 3.13 in) for a piston displacement of 276.1 cu in (4,525 cc). It was replaced by the 301 in 1957, except for in low-priced Plaza models where it continued to be used during the 1957 model year.[2] Power for the two-barrel version is 187 hp (139 kW); this increased to 200 hp (149 kW) for the four-barrel "Power Pack" version which also came equipped with dual exhausts.[3] The Power Pack was also fitted to the Facel Vega FV3, of which 48 examples were built in 1956 and 1957.[4]

301

[edit]

The Plymouth 301 replaced the 277 in 1957 and kept that engine's 3.125 in (79.4 mm) stroke. Its piston displacement is 299.6 cu in (4,910 cc), thanks to the larger 3+29⁄32 in (99.2 mm; 3.91 in) bore. These dimensions are entirely different from the 1955 Chrysler 301. This engine was also installed in the 1957–1958 Facel Vega FV3B.

303

[edit]

The 1956 Plymouth 303 displaces 302.5 cu in (4,957 cc) and uses the same connecting rods as the 277; the bore is 3+13⁄16 in (96.8 mm; 3.81 in) and the stroke is 3+5⁄16 in (84.1 mm; 3.31 in).

This engine was used in the following vehicles:

313

[edit]

A 313 cu in (5,121 cc) version of the A engine called the 313 was produced from 1957 to 1967 primarily for Canadian and export markets. This engine has a bore of 3.875 in (98.4 mm) and the common 3.3125 in (84.1 mm) stroke, and was used in the following vehicles, amongst others:

318

[edit]

The 318 is the most common version of the A engine, produced from 1957 through 1966 in the US and 1967 in some export markets when it was replaced in all markets by the LA 318. Only Plymouth used this 318 in 1957 and 1958, but it was shared with Chrysler from 1959 on and Dodge from 1960 on.[5] It displaces 317.6 cu in (5,204 cc) from a 3+29⁄32 in (99.22 mm; 3.906 in) bore and the 3+5⁄16 in (84.14 mm; 3.312 in) stroke.

A high-performance version called the V-800, offered in 1957 and 1958, used two four-barrel Carter carburetors to produce 290 hp (216 kW), making it the highest-output factory A engine. It was used in the 1957 and 1958 Plymouth Fury, but was also an option on Plymouth models lower in the model range.

Bristol Cars introduced the 318 in the Mark II model of their 408 (in 1965) and continued to use it in the succeeding 409 and 410 until 1969. From 1962 until early 1965, Checker used this engine for their Aerobus limousines.[6]

Non-Plymouth

[edit]

326

[edit]

The 326 was launched in 1959 Dodges. Its actual piston displacement is 325.25 cu in (5,330 cc) but it was marketed as a 326 to avoid confusion with the Dodge Red Ram 325. The 326 uses the same 3+5⁄16 in (84.1 mm) stroke as the 318, but with the largest bore of any A engine at 3+61⁄64 in (100 mm; 3.95 in). It uses hydraulic valve lifters, unlike the other A engines that used solid lifters, and was used in the 1959 Dodge Coronet.

References

[edit]
[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia

Chrysler A engine

View on Grokipedia
from Grokipedia
The Chrysler A engine is a family of small-block V8 engines developed by Chrysler Corporation, introduced in 1956 and produced until 1967, characterized by its innovative polyspherical combustion chambers with canted valves, rear-mounted distributor, and displacements ranging from 277 to 326 cubic inches. These engines were primarily designed for entry-level and mid-range vehicles within the Plymouth, , and lines, offering a , reliability, and cost-effectiveness during the post-war American automotive boom. Evolving from earlier hemispherical-head designs but distinct in its polyspherical architecture—which featured a single head bolt per for simpler manufacturing—the A-series engines were built at Chrysler's Mound Road plant in and the Windsor plant in , emphasizing high-volume automated production. Key displacements included the initial 277 cu in (4.5 L) for 1956 Plymouth models, the 301 cu in (4.9 L) for , the 303 cu in (5.0 L) for some 1956-1957 Plymouth models, the 326 cu in (5.3 L) for 1959 applications, the high-performance 318 cu in (5.2 L) for the 1957 V-800, the Canadian-specific 313 cu in (5.1 L), and the long-running 318 cu in (5.2 L) that became the most common by the early . Bore and stroke dimensions varied accordingly, with the 318 cu in version using a 3.91-inch bore and 3.31-inch stroke, while shared features across the family included 4.46-inch cylinder spacing, a 9.6-inch deck height, 1.84-inch valves, 1.56-inch exhaust valves, and mechanical valve lifters. Power outputs ranged from 187 horsepower for base 277 cu in models to peaks of 290 horsepower in dual-quad carbureted 318 cu in configurations, such as the 1957 Plymouth Fury V-800, with torque figures typically between 330 and 340 lb-ft; compression ratios generally fell between 8:1 and 9.25:1, depending on the application and year. Applications spanned passenger cars like the Plymouth Belvedere and Dodge Coronet, light trucks, and even exports such as the Bristol 407/408 sports cars, as well as marine and industrial uses, though production waned as the more advanced LA-series wedge-head engines supplanted them by 1967. Notable for being Chrysler's last polyspherical-head V8s, the A engines contributed to the brand's reputation for affordable V8 performance but were eventually phased out due to emissions regulations and design shifts toward overhead-valve efficiency.

Overview

Introduction

The Chrysler A engine is an overhead-valve (OHV) V8 engine family featuring polyspherical combustion chambers, introduced by Chrysler Corporation as its first small-block V8 design. Produced from 1956 to 1967, with limited export applications continuing into 1968, the A engine shared a consistent bore center distance of 4.46 in (113.3 mm) across all variants, enabling a range of displacements while maintaining structural compatibility. This engine delivered a general power output of 187–290 (139–216 kW) and up to 350 lb-ft, varying by configuration and application. It served as a cost-effective alternative to the larger and more complex Hemi V8, targeting mid-level models in the Plymouth, , and lineups to provide accessible V8 performance without the premium pricing or manufacturing demands of the hemispherical-head design. The A engine was gasoline-fueled and primarily equipped with 2- or 4-barrel carburetors, supporting both standard and performance-oriented setups.

Key Design Features

The Chrysler A engine family featured polyspherical chambers, characterized by a shallow, rounded, dish-like shape divided into two segments per , which promoted enhanced swirl and in the air-fuel mixture for more complete . This design improved burn efficiency over traditional flathead engines by optimizing flame propagation and reducing unburned hydrocarbons, thereby lowering emissions and enhancing fuel economy without the complexity of hemispherical chambers. The canted valves in a cross-flow arrangement further supported this by allowing better airflow while using a single shaft per head, simplifying manufacturing compared to dual-shaft hemispherical designs. The engine utilized a robust cast iron construction for both the block and cylinder heads, providing durability for high-output applications, paired with a conventional wet sump lubrication system and water cooling via an aluminum-bodied pump. A rear-mounted distributor improved packaging in tight engine bays by positioning it near the firewall, away from front-end accessories. Distinctive scalloped valve covers accommodated the upper spark plug location and exhaust valve springs, while solid mechanical lifters (tappets) were standard, adjusted via rocker arm screws for precise valvetrain operation. Valve dimensions included 1.84-inch (47 mm) intake and 1.56-inch (40 mm) exhaust valves, enabling adequate breathing for the era's performance needs. Compression ratios across the A engine family ranged typically from 8.0:1 to 9.25:1, balancing power and drivability on available fuels. The engine featured full-flow oil filtration, with the filter mounted directly to the block for effective lubrication circulation and engine longevity.

Technical Specifications

Engine Block and Heads

The Chrysler A engine employs a robust deep-skirt cast iron block to ensure structural rigidity and durability under load, featuring cylinders arranged in a 90-degree V configuration typical of its V8 layout. This design allows for efficient heat dissipation and vibration control, with the block's extended skirts providing additional support for the crankshaft and main bearings. The block also includes drilled oil galleries for lubrication distribution and mounting points compatible with Chrysler automatic transmissions such as the PowerFlite, as well as standard manual gearbox bellhousing patterns. Cylinder heads are constructed from with a polyspherical shape, bolted securely to the block using a perimeter bolt pattern that promotes even clamping and sealing. These heads incorporate provisions for the manifold, including aligned ports and passages that facilitate shared fluid flow between the block and heads for uniform temperature management. The polyspherical design positions valves at slight angles for improved airflow, while integral cast features like valve guides enhance longevity and simplify assembly. The cooling system utilizes a belt-driven water pump mounted at the front of the block to circulate through the and passages, regulated by a typically set at 180°F or 195°F to maintain optimal operating temperatures. This setup includes water jackets surrounding the cylinders and heads, with total system capacity ranging from 16 to 20 quarts depending on application, and a radiator cap rated at 14-16 psi for pressure regulation. Coolant flow is directed from the pump through the block to the heads and back to the , ensuring comprehensive thermal control across all variants. Lubrication is provided by a system with a gear-driven pump mounted inside the block and driven by the , delivering full-pressure to critical components via internal galleries. The system holds 5-6 quarts of , with full-flow filtration introduced as standard from to capture contaminants before they reach bearings and other moving parts. pressure is maintained at approximately 15 psi at and 50-65 at cruising speeds, supporting reliable operation.

Valvetrain and Supporting Systems

The Chrysler A engine employs an overhead-valve (OHV) pushrod with a single in-block driven by a timing chain, featuring mechanical flat-tappet lifters and adjustable rocker arms mounted on a central shaft. This design, common across the engine family from its 1956 introduction through 1967, prioritizes durability and low-end through lobe profiles optimized for everyday driving efficiency. The flat-tappet configuration avoids the complexity of hydraulic roller setups, but requires periodic lash adjustments—recommended every 10,000 to 15,000 miles—to maintain optimal and prevent wear on the cam lobes and lifters, a aspect that enhances long-term reliability when followed. The ignition system consists of a rear-mounted with a points-style breaker mechanism, paired with a coil for spark generation, and resistor-type spark plugs to minimize radio interference; single-point distributors were standard until dual-point upgrades in select 1956-1958 performance models for improved curves. The is 1-8-4-3-6-5-7-2, ensuring even power delivery in the 90-degree V8 configuration. The core points system remained prevalent, contributing to the engine's straightforward servicing and robust operation under varied loads. Exhaust systems feature cast-iron manifolds, with single exhaust standard on base models and optional dual manifolds available for enhanced flow in performance-oriented variants like the 1956 ; these setups often incorporated 2.25- to 2.5-inch piping to support increased output without compromising backpressure for . Supporting accessories include provisions for pump mounting on the driver's side of the block, introduced as optional equipment from the mid-1950s onward, and compatibility with factory compressors added during mid-production years around 1955-1956. Electrical upgrades encompassed alternators replacing generators starting in 1960 across products, providing higher output for growing accessory demands while maintaining belt-driven integration with the crankshaft . These elements underscore the A engine's adaptable design, balancing reliability with modular enhancements for diverse vehicle applications.

History

Development and Introduction

The Chrysler A engine was developed in the mid-1950s by Chrysler's engine design team led by engineer Mel Carpentier, with production overseen by resident engineer Willem Weertman at the Plymouth Mound Road V8 engine plant starting in 1954. This new small-block V8 was conceived as a lighter and more affordable alternative to the company's existing polyspheric V8s and premium hemispherical (Hemi) engines, which were costlier to produce due to their complex designs. Evolving from earlier polyspheric designs, the A engine introduced a dedicated small-block architecture optimized for mass production, with features like a compact 4.46-inch bore spacing and integrated components to reduce weight and manufacturing expenses. Initial engineering focused on balancing performance, durability, and economy to meet the demands of entry-level vehicles. Carpentier's team emphasized robust construction, including a and improved lubrication systems, while retaining polyspherical combustion chambers for efficient operation on regular fuel. The design avoided the intricate valve arrangements of the , prioritizing simplicity for high-volume assembly at the newly built Mound Road plant. This positioned the A engine as an accessible V8 option for everyday drivers, contrasting with the performance-oriented Hemis reserved for upscale models. The A engine debuted in 1956 as the "Hy-Fire" V8 in Plymouth vehicles, marking Chrysler's entry into the affordable V8 market dominated by competitors like the Chevrolet small-block and Ford Y-block. Production began in 1955 at the Mound Road and Windsor plants specifically for the 1956 Plymouth lineup, where it displaced the inline-six in mid-range models like the Belvedere. Marketed for its low-end and responsive acceleration, the engine enabled Plymouth to appeal to budget-conscious buyers seeking V8 power without premium pricing, solidifying Chrysler's strategy for broad-market penetration in the post-war automotive boom.

Production and Manufacturing

The Chrysler A engine was primarily manufactured at the Mound Road Engine Plant in , , beginning in July 1955 for domestic production of 1956 models. This facility employed revolutionary automated assembly techniques, including a 656-foot Cross Transfermatic line capable of producing up to 150 engines per hour by late 1955, with synchronized stations for block machining, crankshaft installation, and component assembly. Export assembly occurred at the Windsor Engine Plant in , , supporting Canadian and other international markets. The assembly process featured highly automated for blocks and s using multi-station machines and conveyor systems, minimizing manual labor while incorporating checks like Sheffield gauges for precision tolerances. Components such as pistons, camshafts, and oil pumps were installed with minimal hand-fitting, and completed underwent 20-minute hot testing to ensure reliability before shipping. Most variants utilized mechanical lifters throughout production, with hydraulic lifters appearing only rarely in specific configurations like the 326 cu in version. Early production faced challenges, including water flow issues due to inconsistencies, which were resolved through process adjustments to improve circulation and overall durability. Production of the A engine spanned from 1955 to 1967, when it was phased out in favor of the lighter LA-series small-block V8 for passenger cars in the United States. In and export markets, the A engine continued into 1968, particularly in trucks and industrial applications, before full replacement by the LA design.

Variants

277 cu in (4.5 L)

The 277 cu in (4.5 L) variant served as the inaugural and smallest-displacement member of the Chrysler A engine family, introduced in 1956 exclusively for Plymouth vehicles. It featured a bore of 3.75 in (95.3 mm) and a stroke of 3.125 in (79.4 mm), resulting in a displacement of 276.1 cu in (4.5 L), advertised by as 277 cu in. This configuration provided the shortest stroke among A engine variants, contributing to smoother operation at lower engine speeds compared to larger-displacement siblings with longer strokes. The engine utilized polyspherical combustion chambers in its cast-iron heads for efficient combustion and shared the family's basic overhead-valve design. In its initial 1956 form, the 277 was tuned for economy and everyday performance, equipped with an 8.0:1 compression ratio and a two-barrel carburetor, delivering 187 bhp (139 kW) at 4,400 rpm and 265 lb⋅ft (359 N⋅m) of torque. For 1957 and 1958 models, Chrysler applied minor enhancements including an uprated camshaft and improved intake manifold, boosting output to 197–200 bhp (147–149 kW) at 4,400–4,600 rpm and torque to approximately 270–272 lb⋅ft (366–369 N⋅m). These power figures reflected the engine's economy-focused calibration, prioritizing fuel efficiency and reliability over high-performance aggression, with optional Power Pack upgrades available for added output via a four-barrel carburetor and dual exhaust. The 277 powered a range of entry-level Plymouth models from 1956 to 1958, including the Belvedere, , Suburban, and Plaza sedans and wagons, where it served as the standard V8 option. It was briefly available as an optional engine in select export truck models during this period, though production emphasis remained on Plymouth passenger cars. Overall, the variant's design emphasized balanced, low-end torque for responsive daily driving, cementing its role as the A family's accessible base engine before larger displacements took precedence.

301 cu in (4.9 L)

The 301 cu in (4.9 L) variant of the Chrysler A served as a 1957-specific intermediate displacement option, bored out from the prior 277 cu in version to deliver stronger through increased displacement while maintaining the same length. Its dimensions included a bore of 3.91 in (99.3 mm) and a of 3.125 in (79.4 mm), yielding a total displacement of 299.6 cu in (4.9 L). In base configuration with a two-barrel carburetor, the engine produced 215 bhp (160 kW) at 4,400 rpm, while the optional PowerPak setup featuring a four-barrel carburetor and dual exhaust raised output to 235 bhp (175 kW). Torque was 285 lb⋅ft (386 N⋅m) at 2,800 rpm in the base configuration and 305 lb⋅ft (414 N⋅m) in the PowerPak setup, supporting responsive performance in everyday driving scenarios. This engine powered the 1957 Plymouth Belvedere lineup, where it became the standard V8 for most non-Fury models, and also appeared in Canadian-market exports as an economy-oriented choice emphasizing . Advertisements highlighted its capability for up to 21 highway under optimal conditions, aligning with its role in balancing power and economy. The valvetrain followed the standard A-series polyspheric overhead-valve design detailed elsewhere.

303 cu in (5.0 L)

The 303 cu in (5.0 L) variant of the Chrysler A engine was an export-oriented version developed with a longer stroke to enhance low-end , making it suitable for heavier vehicles in non-U.S. markets. It featured a bore of 3.81 in (96.8 mm) and a stroke of 3.31 in (84.1 mm), resulting in a displacement of 302.5 cu in (5.0 L). This design prioritized delivery for international applications, distinguishing it from domestic variants. Introduced in mid-1956 by , the engine produced 218 (163 kW) with a two-barrel in standard tune. In performance configurations, such as the 1956 Fury equipped with a four-barrel and 9.25:1 , output increased to 240 (179 kW). ratings ranged from 309 lb-ft (419 N⋅m) in base form to 310 lb-ft (420 N⋅m) in higher-output versions. Dual exhaust systems were standard on these performance tunes to support enhanced power and top speeds, as demonstrated in record-setting runs exceeding 148 mph. Primary applications included the 1956-1957 Canadian and Australian and models, where it served as the standard V8 for larger sedans and coupes. It also powered the 1956 as its standard engine, sourced from Canadian production for this U.S. model, emphasizing its use in performance applications. In 1957, it extended to Canadian Plymouth and vehicles on 118-inch wheelbases, bolstering Chrysler's presence in Commonwealth regions.

313 cu in (5.1 L)

The 313 cu in (5.1 L) variant of the Chrysler A engine was an underbored derivative of the 318 cu in design, featuring a bore of 3.88 in (98.6 mm) and a of 3.31 in (84.1 mm), resulting in a displacement of 312.5 cu in (5.1 L). This configuration allowed for power outputs of 250 bhp (186 kW) at 4,400 rpm when equipped with a four-barrel , paired with approximately 340 lb⋅ft (461 N⋅m) of . The engine maintained the polyspherical combustion chambers and overhead-valve setup of the A-series family, contributing to its smooth operation and reliability in demanding international environments. Primarily developed for Canadian production and export markets, the 313 cu in engine debuted in the 1957 Dodge Custom Royal and served as the standard V8 for midsized Plymouth and Dodge models in Canada from 1958 through 1964, with some applications extending into 1965 Canadian vehicles. It also found use in export Plymouth and Dodge models during 1957–1959, where its compact dimensions and robust construction proved durable for varied global conditions, including heavier loads and less-than-ideal fuel quality. Notably, the engine powered British sports cars such as the Bristol 407 (1961–1963) and early Bristol 408 (1963–1964), where it delivered strong low-end torque for agile grand touring performance. A key unique feature of the 313 cu in variant was its slightly reduced bore compared to the domestic 318 cu in engine, implemented to comply with export regulations such as the U.K.'s (R.A.C.) taxable horsepower formula, which penalized larger bores through higher road taxes. In applications, some tunes retained the standard hydraulic lifters for quieter operation, while others incorporated modifications like higher-lift camshafts with mechanical lifters to enhance high-rpm capability and durability under sustained use. This adaptability underscored the engine's versatility and longevity in specialty and international roles, often exceeding 100,000 miles with minimal issues when properly maintained.

318 cu in (5.2 L)

The 318 cu in (5.2 L) variant of the Chrysler A , introduced in 1957, featured a bore of 3.91 in (99.3 mm) and a stroke of 3.31 in (84.1 mm), resulting in a displacement of 317.6 cu in (5.2 L). This configuration made it the largest and most versatile displacement in the A family, with the polyspherical combustion chambers and canted valves contributing to efficient airflow and power delivery across a broad range of uses. As the most produced version, it became the domestic mainstay, outperforming smaller variants in and adaptability for heavier applications. Power outputs varied by configuration and year, starting with the base two-barrel carburetor version rated at 225 bhp (168 kW) from 1957 to 1967, while the optional four-barrel Super-Pak tune delivered 250 bhp (186 kW) in models like the Plymouth Fury from 1957 to 1962. The high-performance dual-quad setup, exclusive to the 1957-1958 Plymouth Fury, achieved 290 bhp (216 kW) with dual Carter WCFB carburetors and 9.25:1 compression. In truck applications, later net ratings dropped to around 200 bhp (149 kW) by the mid-1960s to reflect emissions and efficiency standards. Torque ranged from 286 to 340 lb⋅ft (388 to 461 N⋅m), with the peak of 340 lb⋅ft (461 N⋅m) in 1959 models equipped with the four-barrel carburetor and 9:1 compression. These figures highlighted the engine's strong low-end pull, ideal for acceleration and hauling. The 318 saw widespread use in passenger cars such as the , , and Coronet from 1957 to 1967, as well as in and trucks for light- and heavy-duty roles. It also powered specialty vehicles like the Checker Aerobus taxi-limousine through the mid-1960s. In industrial applications, the H318 variant produced 190 hp (142 kW) for equipment like delivery trucks, pumps, and concrete mixers from 1959 onward. Marine adaptations under the M318 designation, such as the Chrysler Sea V and Fury series, delivered 177 to 235 hp (132 to 175 kW) with features like splash-proof ignition and water-jacketed exhaust manifolds for boat propulsion from 1959 to 1967. Unique to the 318 was its status as the most common A engine block, benefiting from optional four-barrel intakes and high-compression cylinder heads that allowed tuning flexibility without major redesigns. Production continued beyond 1967 in non-automotive roles, including industrial and marine sectors, extending its service life well into the due to its durability and parts availability.

326 cu in (5.3 L)

The 326 cu in (5.3 L) variant represented the largest and most powerful iteration of the Chrysler A engine family, introduced exclusively for the as a high-output option tailored for passenger cars. With a bore of 3.95 in (100.3 mm) and a stroke of 3.31 in (84.1 mm), it delivered an actual displacement of 325.2 cu in, though marketed as 326 cu in to differentiate it from the preceding Dodge 325 polyspherical V8. This overbored design from the 318 cu in base emphasized top-end power and for performance-oriented applications, while maintaining the A series' polyspherical chambers for efficient breathing. Equipped with a 9.2:1 compression ratio and a two-barrel carburetor, the engine produced 255 bhp (190 kW) at 4,600 rpm and 350 lb⋅ft (475 N⋅m) of torque at 2,400 rpm. Unlike other A engine variants that relied on solid valve lifters, the 326 incorporated hydraulic valve lifters for quieter operation and reduced maintenance, a feature unique within the family that enhanced its suitability for refined passenger car use. Heavy-duty internal components, including reinforced pistons and bearings, supported its role in delivering robust low-end torque for acceleration and light towing duties. This short-lived variant was fitted standard in the 1959 Dodge Coronet V8 models and optional in the Custom Royal lineup, powering sedans, hardtops, and convertibles with a focus on mid-range performance. Limited production emphasized its role as a bridge between the economy-focused smaller A engines and the larger B-series wedges, appearing briefly in select export markets before discontinuation after 1959.

References

  1. https://www.motales.com/engines/A-V8.php
  2. https://poly318.com/poly-318-engine-history-information/
  3. https://autohistorypreservationsociety.org/the-1956-1967-plymouth-polyspherical-head-explained/
  4. https://www.allpar.com/mopar/poly.html
  5. https://www.allpar.com/mopar/a-engines.html
  6. https://www.allpar.com/threads/semi-hemi-polyspherical-head-v8-engines-241-259-270-301-315-325-331-354.229880/
  7. https://poly318.com/poly-318-manufacturing-engine-plant/
  8. http://www.chrysler300clubinc.com/jholst/55-service-manual/transmission.pdf
  9. https://poly318.com/poly-318-engine-specifications/
  10. https://poly318.com/poly-318-cooling-thermostat-overheating/
  11. https://desoto.org/community/general-discussion/oil-filters-issues-what-brand-do-you-like/
  12. https://help.summitracing.com/knowledgebase/article/HE-04935/en-us
  13. https://alternatorparts.com/chrysler-alternator-history.html
  14. https://www.allpar.com/d3/corporate/bios/weertman-chron.html
  15. https://www.enginelabs.com/engine-tech/polyspheric-semi-hemi-engines-chrysler-creativity-or-cheap-junk/
  16. https://www.motales.com/engines/LA-based/LA-318-360.php
  17. https://www.bigblockmopar.nl/tech/engine/mopar-engine-size-bore-and-stroke-specifications/
  18. https://www.over-drive-magazine.com/2025/09/19/1957-plymouth-fact-sheet/
  19. https://www.automobile-catalog.com/car/1957/2641355/plymouth_belvedere_sport_coupe_301_fury_v-8_powerpak_kp31.html
  20. https://www.automobile-catalog.com/performance/1957/2642135/plymouth_savoy_club_sedan_301_fury_v-8_powerpak_kp31.html
  21. https://www.allpar.com/threads/plymouth-fury-1956-1974-from-top-muscle-to-family-sedan.228767/
  22. https://bangshift.com/general-news/videos/happy-3-13-check-out-this-export-only-chrysler-a-block-as-it-sings-on-the-dyno/
  23. https://fastestlaps.com/models/bristol-407
  24. https://www.forcbodiesonly.com/mopar-forum/threads/313-super-red-ram.20149/
  25. https://www.xr793.com/wp-content/uploads/2022/04/1960-Chrysler-AP3-Royal-6-or-V8-AUS.pdf
  26. https://www.bristolcars.info/forums/8-10-cyl-bristol-cars/2042-special-313-engines-407-408-mk1.html
  27. https://www.curbsideclassic.com/curbside-classics-american/lodgeside-classic-checker-aerobus-twelve-passengers-eight-doors-four-on-the-floor/
  28. https://poly318.com/poly-318-marine-industrial-engines/
  29. https://www.allpar.com/threads/all-engines-used-in-chrysler-corporation-cars-and-trucks.229992/
  30. https://www.automobile-catalog.com/car/1959/597950/dodge_coronet_v-8_4-door_sedan.html
  31. https://forums.aaca.org/topic/357969-chrysler-poly-engine-production-numbers/
  32. https://www.hagerty.com/media/opinion/1959-dodge-coronet-wild-crazy-and-totally-awesome/
  33. https://www.curbsideclassic.com/curbside-classics-american/curbside-classic-1959-dodge-coronet-sedan-chrome-fins-and-more-chrome/
Add your contribution
Related Hubs
User Avatar
No comments yet.