Austin Powers: The Austin “A” Series Engine in the Lotus Seven Series 1


Subscribers are directed to A&R article “Lotus Power Plants” in order to see the various proprietary engines fitted by Lotus and the reasons for doing so. The adoption and mutation of technology and componentry is a significant act within Industrial Design. It can have creative and commercial advantages of added value.

One of the most important proprietary engines used by Chapman was the A Series Austin.

A quotation by Simister in “Legendary Car Engines” sets the scene and context.

“Little did Austin know that its engine for the A30, a car introduced in 1952, would still be in production nearly half a century later.

It has powered many of Britain’s best loved small cars and stretched and tuned far beyond its original designers dreams .This is the story of the BMC-A Series ; Britain’s most enduring engine.”

This article is not a Haynes manual type of how to rebuild or tune the Austin engine. Rather is a look at the way they were adopted by Chapman and their importance.

The Austin A Series Engine

The editors believe that the primary engineers / designers responsible for the Austin A Series were:-

  • Eric Bareham
  • Bill Appleby
  • Johnnie Rix

In “Legendary Car Engines” Simister summarizes the characteristics of the A series:-

  • Humble but successful design rooted in long stroke heritage
  • Plenty of torque and low speed pulling power associated with heavy flywheel
  • Camshaft timing orientated to torque delivery
  • Long stroke contributed to thermal efficiency and excellent fuel consumption
  • Narrow ,tall block consistent with bore /stroke
  • Combustion chamber necessitated small valves
  • Sweet running
  • Electrical equipment located to right , induction to left
  • Siamese ports
  • Made 1952-2000, capacity ranging from 803 to 1275cc

Engines [edit] From the Net:

  • 1956–1962 – 948 cc A-Series I4, 34 hp (25 kW) at 4,750 rpm and 50 lb·ft (68 Nm) at 2,000 rpm
  • 1962–1966 – 1,098 cc A-Series I4, 55 hp (41 kW) at 5,500 rpm and 61 lb·ft (83 Nm) at 2,500 rpm (Van)
  • 1963–1968 – 848 cc A-Series I4, 34 hp (25 kW) at 5500rpm and 44 lb·ft (60 N·m) at 2,900rpm (Van)

BMC A-Series engine

Austin Motor Company‘s small straight-4 automobile engine, the A-Series, is one of the most common in the world. Launched in 1951 with the Austin A30, production lasted until 2000 in the Mini. It used a cast-iron block and cylinder head, and a steel crankshaft with 3 main bearings. The camshaft ran in the cylinder block, driven by a single-row chain for most applications, and with tappets sliding in the block, accessible through pressed steel side covers for most applications, and with overhead valves operated through rockers. The cylinder head for the overhead-valve version of the Austin series A engine was designed by Harry Weslake – a cylinder head specialist famed for his involvement in SS (Jaguar) engines and several F1 title winning engines.


Figure 1Editors sketch of Austin A30-engine and gearbox


The car’s newly designed A-Series straight-4 engine was state of the art for the time and returned an average fuel consumption of 42 mpg / under 7L/100 km. With spirited driving the A30 was able to attain a top speed of 70 mph (110 km/h) (factory quoted). In their road test The Motor magazine achieved a top speed of 67.2 mph (108.1 km/h) and a 0–60 mph time of 42.3 seconds. Braking was effected by a hybrid system, with Lockheed fully hydraulic drum brakes at the front and a body mounted single cylinder operating rods to the wheels at the rear, which despite being heavily criticised as being archaic and old-fashioned, were reported as being quite acceptable. The rod system provided good handbrake efficiency and was applied by a lever in an unorthodox position to the right of the driver’s seat (Right hand drive vehicles). Bumps were handled by independent coil springs at the front end and beam axle/semi-elliptic leaf springs at the back.

A car tested by The Motor magazine in 1952 had a top speed of 62 mph (100 km/h) and could accelerate from 0–50 mph (80 km/h) in 29 seconds. A fuel consumption of 38.8 miles per imperial gallon (7.28 L/100 km; 32.3 mpg-US) was recorded. The test car cost £553 including taxes. The optional radio was an extra £43 and the heater £9.[7] Performance data need to be seen in the context of fuel availability. Early in the Second World War “branded fuel” disappeared from sale in the UK, and the nationally available fuel available at the beginning of 1952 had an octane rating of just 70, which enforced relatively low compression ratios: this reduced the performance available from all cars, especially small ones. In 1952 branded fuels returned to the forecourts, available octane ratings began to increase, and compression ratios were progressively improved along with the performance figures of cars such as the Austin A30 and its A35 successor.[8]


Figure 2.Austin A30 seen from other side


Figure 3.Pair of editor’s sketches showing both sides of Austin A35 engine/gearbox


Figure 4.Editors sketch to emphasise relative scale

Standard Engine Data

Marque Model Bore Stroke CC Net BHP Rpm C’Ratio Carbs
Austin 7 63 68 848 31.5 5500 8.3 1 Zenith
Austin A35 63 76 948 4750 8.3 1 Zenith
Austin Sprite 63 76 98 42.5 5200 8.3 2 S.U.
Ford Popular 63 92 1172 36 4500 7 1 Solex
Ford Prefect 81 48 997 39 5000 8.9 1 Solex
Ford Consul 82 79 1703 59 4400 7.8 1 Zenith
Hillman Minx 79 76 1494 53 4600 8.5 1 Zenith

Power of Seven

The Austin A Series Engine was a popular option in the Lotus Seven Series 1.

It’s possible that owners and particularly those engaged in racing updated their cars with the uprated A Series engines over time including carburetors etc.

The illustrated magazine advertisement calls attention to the use of the engine in the Austin A35.

The Lotus Seven -BMC “A” Series Engine Context

Tony Weale observes that:-

“………the small BMC engine started a very successful production run in 1953 with a capacity of 803 cc. Succesively enlarged and refined ……… formed the power unit of many different cars being rugged, reliable and capable of tuning for almost any purpose.

The A series is a pushrod overhead valve engine with a cast iron block and cylinder head, and though of traditional long stroke design its efficient cylinder head layout has given it an excellent reputation for power and economy .For its size its heavy and strongly built engine. Rear wheel drive versions have been produced in capacities of 803 850, 948, 1098 and 1275 cc ………….the best of the smaller capacities are the 948 cc engines ………………the 1275 engines fitted to late Sprites and the Marina/Ital range are arguably the best in line A series engines of all …………….. A typical A series engined Lotus Seven of 1960 would have been fitted with an Austin-Healey Sprite specification engine of 948 or 1098 cc with single or twin SU carburetors developing between 40 and 65 bhp……….Even with the lowest powered A series engine , performance would have been better than that of the equivalent 100E –engined Seven, as a result of the BMC’s four speed gearbox and free revving character…………..indeed it was better liked in some quarters than the original 997 cc Ford 105 E powered Sevens.”

Whereas Tipler comments that:-

“The Series 1 Seven A came out in October 1959 and used the 950 BMC A series engine with twin SU carburetors normally found in the Austin Healey Sprite. It particularly appealed to US customers since there was an established BMC dealer network for servicing.”

Coulter adds:-

“Introduced at Motor show in October 1959.

Engine: BMC A series Austin A35 or Morris Minor 948 cc four cylinder overhead valve. Bore 62.94mm, stroke 76.2mm .Compression ratio 8.9:1.Single SU carburetor .37 bhp at 4,800 rpm .Versions for USA designated “Seven America” used basically similar engine from Austin Healey Sprite with 8.3:1compression ratio, twin SU carburetors, and 43 bhp at 5,200 rpm

Comparative Data: Engine Derivatives

Marque Austin Austin Austin Austin
Model A30 A35 Healey Sprite[America] Healey Sprite Mk4
Years 1951-1956 1956-68 1958-61 1966-70
Prod ‘No’s 222,823 all types 353,849 48,999 21,768
Engine A series A series BMC A series BMC A series
cylinders 4 in-line as A30 4 in-line 4 in-line
valves ohv as A30 ohv ohv
cc 803cc 948cc 948cc 1,275cc
bore/stroke 58×76.2mm 62.9×76.2mm 62.9×76.2mm 70.6×81.28mm
bhp 28@4800rpm 34bhp@4750rpm 43bhp@5200rpm 65bhp@6000rpm
Arnold [37gross bhp]
Torque Arnold 50lbft 2500 rpm Arnold 52lbft3300rpm
Compression R’ Arnold 8.9to1 Arnold 8.3 to 1
gearbox 4 speed as A30 4speed 4-speed
Carbs Arnold 1-S/D SU H2 Arnold 2-S/D SU H2
max.speed 62mph 72mph 86mph 94mph
0-50mph 29sec 0-60=30sec 0-60=20.5sec 0-60=14.1sec
standing 1/4m 26.5sec 23.5sec 21.8sec 19.6sec
o’all fuel consum’ 42mpg 40mpg 34mpg 30mpg
Marque Morris MG
Model Minor 1000 Midget
Years 1956-62 1961-64
Prod ‘No’s 554,084
Engine BMC A series
cylinders 4 in-line
valves ohv
cc 948cc 948cc
bore/stroke 62.9×76.2mm 62.9×76.2mm
bhp 37bhp@4750rpm 46bhp@5500rpm
gearbox 4speed
max.speed 73mph
0-50mph 0-60=25.9sec
standing 1/4m 23.4sec
o’all fuel consum’ 38mpg
0-60 14.2sec 13.8sec
standing 1/4m 19.1sec 19.sec
max.speed 80.2 mph 80.5mph
o’all fuel consum’ 37.7mpg 38.3mpg

Estimated Performance for Series 1 Seven A [948cc Austin engine]

0-60 mph 14.2 sec’

Standing Quarter 19.1 sec’

Top speed 80.2 mph

Fuel Consumption 37.7 mpg

[Nb Coulter quotes comparative figures for most of the models statistics taken from official published road tests but not for Austin engine in S1 form]

The configuration and nature of the A Series engine was such that fuel economy was an advantageous characteristic

Retail Prices

Quoted from Coulter:-

Seven Series 1 [F] Ford

Kit £536

Complete £690 approx. Tax £347 approx. Total £1036 approx.

Super Seven [Coventry Climax 1098cc]

Kit £499 Engine£356 [£892] Total £1,546

Seven Series 1 [A] Austin

Kit £511

Drawing of Austin Engine in Lotus Seven Series 1

The editors have produced a composite drawing from materials within the A&R. The main sources of inspiration coming from:-

  • The Magnificent Seven-Rees
  • Lotus and Caterham Seven-Tipler
  • Lotus Seven –Weale
  • Lotus Seven-Ortenburger

NB: The editor has left out some of the “plumbing and wiring” to concentrate on the primary focus of the engine installation in the chassis. [Along with the impact on form and function;] and partly to avoid visual distraction.


Figure 5.Editors sketch Single carburettor engine. Seven Series 1


Figure 6.Editors sketch: Twin Carburetter engine. Seven Series 1


Figure 7.Editors sketch -subscribers directed to our article on “Colouring Cars” and engine detailing etc. Seven Series1

Note the A Series engine was available in various levels of tune which included single or twin carburetors.

As stated above the editors believe that some owners might have upgraded their cars with later A Series “1275” engines and appropriate carburetors. In the top picture the editor has shown that a period modification was to improve cooling and accessibility of the radiator filler by slightly increasing capacity and refitting the filler within the engine bay area , where it was more easily reached when the bonnet was removed as opposed to the frig of removing the nose cone.

Tuning Conversions


Alexander was a popular aftermarket tuning range of equipment for the Austin engine. Subscribers are invited to see our dedicated article where we expand on history and applications.


Figure 8.Editors sketch of Alexander twin carburetter conversion on Morris engine

Learning Opportunities

Our learning /educational opportunities are intended to be challenging thought provoking and requiring additional research and/or analysis.

These opportunities are particularly designed for a museum/education center location where visitors would be able to enjoy access to all the structured resources available in conjunction with any concurrent exhibition.

In this instance we suggest the following might be appropriate:-

  • Examine and counter balance costs and performance of respective engines available in Seven S1. [ draw graph for example]
  • Admittedly not easily achieved but guestamate respective sales numbers for each engine option-Seven Series 1&2
  • Examine the relationship between proprietary engine /gearbox and its impact on both performance and customer preference
  • Examine physical proportions of Seven to understand how various engines were fitted without spoiling the aesthetic
  • Examine relative ease and engine mountings noting that engine came from “shell” body frame as was used in tube frame chassis.
  • Consider and possibly list after market and tuning accessories available for respective engines and postulate if this might influence purchase

Exhibitions, Education and Economics

In the museum context the editors believe that commercial considerations are both necessary and complementary with its educational objectives.

For these reasons our suggested outline Business Plan includes provision for promoting products and services which share Chapman’s ideals of mechanical efficiency and sustainability. In addition we propose merchandising that explain and interprets the technical, social and cultural context of Chapman’s designs in period. It’s suggested there will be catalogue for on line purchasing.

An exhibition of the various proprietary engines used by Lotus provides many interesting permutations, visual stimulus education /learning opportunities ranging from engineering to economics to Industrial Design.

In addition cars from manufacturers can be counterpoised with Lotus to reinforce both similarity but also Chapman’s creative reuse /interpretation. The exhibition could also contain the tuning modifications and racing cars that used Austin engines. Not least it’s an opportunity to explain British engineering history and development in both the mass car and specialist car markets.

The editors believe that a truly modern hands on and interactive museum will involve cars being seen , driven and heard by visitors and that a holistic and all round sensory learning experience can be provided.

Suggested exhibition titles include:-

  • Agent Austin
  • Austin: Apparatus & Appliances in Lotus Seven S1&2
  • Lotus 7A and the Engine of Change
  • Austin England to Lotus America: The Lotus Seven A
  • Austin crosses Atlantic to America Seven S1A
  • Austin Long stroke engine:Chapman’s stroke of genius for Lotus 7S1&2


Chapman/Lotus used proprietary engines to great effect conferring considerable added value in the process. Of course later it was necessary and desirable to produce their own.

Proprietary engines were relatively inexpensive, well known, respected with spares and serving centers. Therfore they could be bought with confidence.

They were the perfect complement to Chapman’s formula and offered customers an assurance that they might obtain the best of both worlds.

The Austin engine could be tuned. Although generally utility it was not unattractive and did not look out of place in the Seven S1&2.

Furthermore the relatively low capacity engines like the Austin A series were essentially sustainable and fuel economic .The great legacy is that many are still used and raced today.

Austin engines were used at Hornsey and continued at Cheshunt in the Seven S1&2.


Subscribers are directed to our articles on Lotus Seven and Power Plants that contain an extensive bibliography. Of special interest are:

Legendary Car Engines.Simister.Motorbooks.2004.

ISBN: 0760319413

The Magnificent Seven.Rees.Haynes.2007.

ISBN: 9781844254101

Lotus & Caterham Seven.Tipler.Crowood.2005

ISBN: 1861267541

Lotus Seven.Weale.Osprey.1991.

ISBN: 185532153X

Lotus Caterham Seven. Unique Books.

ISBN: 1841553778

The Lotus & Caterhan Sevens.Coulter.MRP.1986.

ISBN: 0947981063

Lotus Seven and the Independents.Ortenbergher

Industrial Design A-ZC&P Fiell.Taschen.2000.

ISBN: 3822863106

Legendary Car Engines.Simister.Motorbooks.2004.

ISBN: 0760319413

Tuning BL’s A Series Engine.Vizzard.Haynes.1991.

ISBN: 0854297324

Austin A30&A35 Running and Maintenance Instructions.The Austin Motor Company, 1956 1958

Austin A30, 35.Nelson.Olyslager Manual No29…1969

The Last Real Austin’s, 1946-1959.Veloce.

ISBN: 9781845841935

The Cars of BMC.Robson.MRP.1999.

ISBN: 1899870415

The A&R also possesses an extensive range of tuning, servicing and maintenance manuals [factory and proprietary] for the A Series engine s fitted in the A30/35, Mini and Austin Healey Sprite.

Please note the editors of the A&R attempt to give the broadest spectrum of references but not all are available for consultation in an article. However by noting their existence it may assist students in their research.

*Items in italics non A&R library books.