Ac · 1965–1973

AC Frua

The AC 428 is a British Grand Touring (GT) automobile built by AC Cars from 1965 to 1973. Originally called the AC 427, it is also known as the AC 428 Frua, for the carrozzeria that designed and produced the body. Production totalled 81 cars: 51 fastback coupés and 30 drophead coupés.

Text from Wikipedia (CC BY-SA 4.0).

Predecessor: AC Greyhound · Successor: AC 3000ME

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History

=== Advent of the Cobra 427 === After losing the 1964 World Sportscar Championship to Ferrari's GTOs, and facing the imminent arrival of 427 cu in (7.0 L) Corvettes in American sportscar classes, Carroll Shelby commissioned a complete redesign of the Cobra 289 that resulted in the Cobra 427. A new Mark III ladder chassis and all-independent suspension were designed with input from both Ford and AC and extensive use of Ford's computer-assisted design resources. The revised chassis was better able to handle the output of Ford's 7-litre "427" FE V8, and the new suspension provided more travel. The first MkIII chassis with 427 powertrain was built in October 1964, and the first finished Cobra 427 was shown to the public in Riverside, California in January 1965. Cobra 427 homologation problem. Shelby's next hurdle was to produce the 100 cars needed to have it homologated, but by late February only 53 cars had been built. The FIA declined to homologate either the Cobra 427 or Ferrari's new 250 LM for the 1965 season. Shelby was left to dispose of over 50 copies of a race car ineligible for the events it was designed for. He instructed AC to halt production of the cars, and converted approximately 30 of the racecars to street-legal S/C models. AC began looking for projects of their own that would make them less dependent on work coming from Shelby American. Related projects. By this time some consideration had already been given to possible successors of the Ace and small-block Cobra. In 1962, with work on the AC Cobra already underway, AC had a planned successor to the Ace in development. A single prototype of the car, called the MA-200, was produced. The majority of the engineering work on the MA-200 was done by AC's Polish engineer and former MIG designer, Zdzislaw Teofil (

Features

=== Chassis and body === The AC 428 is built on what is essentially an AC Cobra 427 Mark III chassis extended by 6 inches (152 mm). Although the 4-inch (102 mm) diameter tubular chassis main members are sufficiently rigid for both coupé and convertible versions, the design is intricate and prone to rust. While some references say that the original prototype CF 1 had an all-aluminium body, with a supporting structure of small-diameter square and round tubing somewhat similar to Touring's Superleggera technique, others say that even the first body was mainly steel, with the bonnet and boot lids made from aluminium. Production bodies were of steel. Running gear. The AC 428 inherited the MkIII chassis' fully independent coil spring suspension, making it stand out among its live axle contemporaries like the Iso Grifo, Iso Rivolta, Monteverdi, and De Tomaso models. At the front is a double wishbone suspension with coil springs and telescopic dampers, while in back are upper wishbones and lower reversed wishbones with short additional radius rods. Powertrain. The production AC 428 is powered by a Ford FE "428" V8 engine that actually displaces 427 cubic inches (Ford's "427" FE engine likewise actually displaces 426 cubic inches). This overhead valve engine has a cast iron cylinder block and heads, a single cam-in-block, two valves per cylinder, cross-bolted mains, and wedge shaped combustion chambers. The FE 428 used in the AC has Ford's Police Interceptor tuning package. Two transmissions were used: a close-ratio 4-speed manual Ford Toploader transmission was used in the first three cars, while a 3-speed automatic Ford C6 transmission was in all subsequent examples. All cars received a Powr-Lok limited-slip differential, with a final drive ratio of 2.88:1.

Performance

Autocar published a road test report in 1968 of a 428 coupé, and recorded a maximum speed of 141 mph (227 km/h) along with a 0–60 mph (0–97 km/h) time of 6.2 seconds. The acceleration time was fractionally better than the magazine had achieved with an Aston Martin DB6, but the Aston was comfortably ahead on top speed. The AC's overall fuel consumption for the test came in at 15.6 mpg‑imp (18.1 L/100 km; 13.0 mpg‑US), roughly 15% better than the heavy Aston Martin. The AC 428 coupé with automatic transmission sported a suggested UK retail price of £5,573, to the manual-equipped Aston Martin DB6's £4,460 - itself roughly twice that of a 4.2-litre Jaguar E-Type roadster at £2,225.

Technical details

== Later projects and customs == Towards the end of 428 production, prototypes for two possible successor models were produced. Neither was developed due to the precarious state of the company's finances. AC 429. A prototype 2-door, 4-seater saloon powered by a 7-litre Ford V8 was first seen at Thames Ditton in 1969. Referred to as either the AC 429 or the AC 7-litre Saloon, it was built on an existing monocoque platform provided by Frua that is based on a Monteverdi 375 L. The car received a new rear suspension developed by AC, replacing its original de Dion axle, and a new steering system incorporating parts from Alford & Alder. Work on the car continued until 1971. The engine was still from Ford, but it is unclear whether this car was named "429" as the numeric successor to the 428 while keeping the Ford FE "428" engine, or had an actual 429 cubic inch V8 from the American company's 385 engine family. 1971 428 Spider II. Late in the 428's production life, Frua created an updated convertible with revised rear lines and hidden headlamps. A running version was finally completed in the winter of 1981/82, almost ten years after the end of regular production, after which the prototype was used by Derek Hurlock as his personal car. AC 428 Spider by Luigi Colani. Designer Luigi Colani bought chassis CFX 32 and built a unique spider body for it in 1986.

Sections adapted from Wikipedia (CC BY-SA 4.0); text is shortened. Read the full article for the complete history and citations.

Specifications

name

AC 428

Manufacturer

AC Cars

aka

AC 427, AC 428 Frua

Production

1965–1973, 81 made

Designer

Pietro Frua

Class

Sports car (S)

Body style

2-door drophead coupé, 2-door fastback coupé

Related

Cobra 427

Engine

Ford FE "428" V8

Transmission

4-speed manual, 3 speed automatic

Wheelbase

96 in

Length

174 in

Width

67 in

Height

51 in

Kerb weight

3143 lb

sp

uk

Specification summary from Wikipedia (CC BY-SA 4.0). Measured facts from Wikidata (CC0). Check the linked sources for citations.

More photos

Sources

• Wikidata — https://www.wikidata.org/wiki/Q288913CC0 1.0 · retrieved 2026-10-01
• Wikipedia — https://en.wikipedia.org/wiki/AC_428CC BY-SA 4.0 · Text © Wikipedia contributors; revision 1370111484 · retrieved 2026-10-01
• Wikimedia Commons — https://commons.wikimedia.org/wiki/File:Ac_Frua_Roadster.JPGPublic domain · Photo: EmmanuelD at English Wikipedia · retrieved 2026-10-01
• Car Model Index — https://models.autoculturesociety.com/Compiled record. Sources that do not permit reuse are not copied; this index is credited instead.

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