Monday 22nd July 2019,

Jaguar XK120 Sports 1948 – 1954

Jaguar XK120 1948-1954
The motor industry was still struggling to revive after the war when Bill Lyons unveiled the revolutionary Jaguar XK 120 in 1948. Lyons, Bill Heynes, Claude Bailey and Wally Hassan had worked, almost by candlelight, throughout the war years to produce a world-beater.

The heart of the project was the engine. The XK 3.4 litre was a masterpiece that went on, through countless revisions, to finally retire in 1992. Although twin-cam engines were quite common before the war the XK showed what genius and development could produce in spite of war-production taking priority over everything industrial. The XK was not only a twin-cam. It had an alloy cylinder-head with hemi-spherical combustion chambers and inclined valves, re-discovered by American makers much later.

Twin SU carburetors were standard equipment. The secret of it`s legendary reliability lay in the basic design. The smooth conversion of combustion to brake horse power was achieved by `designing out` stress on the moving parts. This was done by lightening and balancing the dynamic components including the fly-wheel. The result was a rating of 160 bhp with 8 to 1 compression ratio.

The 4 speed gearbox used in the XK 120 was designed and built by Jaguar. Front suspension was by way of independent torsion bars, the rear by semi-elliptic leaf springs and the steering mechanism was `recirculating ball`. Drum brakes were the only brakes available at that time and severely affected the `driveability` of the XK 120 and every other car of the period. They were big, (12 inch diameter), but even with the modern aluminium finned (Alfin) drums the braking was woefully inadequate.

Body design;

Initially, the Jaguar XK 120 was hand-built in the traditional fashion, with a skeleton chassis, ash timber frame and alloy skin. The first 242 cars, two years` production, were built like this. In 1950 the huge demand for the car necessitated the use of a pressed steel bodyshell, which did not need ash framing. This decision vastly improved mass production. The steel car still used aluminium bonnet, doors and boot-lid though. The streamlining rear wheel-arch spats were also alloy but on cars with wire wheels (from 1951) they were dispensed with.

Body types;

The XK 120 was initially introduced as a roadster. To clarify, the term `roadster` has, in modern times been attached to drop head coupes (DHC). In fact, the roadster was quite different. The XK 120 roadster had a windscreen frame that could be removed and replaced by aeroscreens. Normally there was no weather equipment apart from a tonneau cover for the cock-pit.

A weather equipment package option was made available on the steel cars in 1950 which consisted of a light-weight canvas roof and canvas side-screens. If the car had aeroscreens fitted the driver just got wet as there was no way to fit a roof. In 1953 Jaguar offered the drop-head coupe version of the XK 120. This had roll-up side windows, quarter-light windows and a fully lined, folding top. On this model the windscreen frame was built into the body and was painted to match the body-colour, much like modern cars. In 1951 the fixed-head coupe (FHC) had been introduced to appeal to the less intrepid market, with a fixed roof and windows that fitted. All cars were fitted with a two-piece windscreen.

The DHC and FHC versions had a veneered dashboard whereas the roadster had a leather covered dash for weather reasons. The XK 120 had considerable competition success (particularly the roadster). The Jaguar XK 120 also won the accolade of the fastest production car in the world.

In 1951 the XK 120 SE became available. This `special equipment` version included wire wheels, `C type` cylinder-head, stiffer suspension and twin exhausts. The car continued successfully until replaced by the XK 140 in 1954. It is a very collectable car today.

Jaguar XK120 1948-1954
Body Type2 seater roadster/Drophead coupe/Fixhead coupe
Engine PlacementFront
Drive TypeRear wheel drive
Height (FHC)135953.5
Cargo VolumeVery respectable
Engine3.4 Jaguar XK 12V DOHC Hemispherical
Cylindersstraight 6
Displacement3442 cc210 cui
Power119 Kw160 bhp5000 RPM
Torque264 Nm195 ft. lb2500 RPM
Power/weight124 bhp/t
Top Speed201 km/h125 mph
Acceleration0-100 km/h - 0-60 mph10 s
Fuel consumptionl/100 kmImperial mpg
Gearbox4 speed manual
Weight1295 kg2855 lb
Engine3.4 SE Jaguar XK 12V DOHC Hemispherical
Cylindersstraight 6
Displacement3442 cc210 cui
Power134 Kw180 bhp5300 RPM
Torque275 Nm203 ft. lb4000 RPM
Power/weight134 bhp/t
Top Speed217 km/h135 mph
Acceleration0-100 km/h - 0-60 mph8.7 s
Fuel consumptionl/100 kmImperial mpg
Gearbox4 speed manual
Weight1346 kg2967 lb
GD Star Rating
Jaguar XK120 Sports 1948 - 1954, 8.5 out of 10 based on 4 ratings
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About Bev Roberts

Speed, the smell of hot oil, the roar of a straight-through exhaust and the scream of an engine at max revolutions. They have all been a large part of my life for almost 50 years. It is time to share my experiences with you, dear reader. Do you want to know more? Read on through my `Full Bio` and many articles.

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I was born in Hereford UK in 1948 and brought up in Gloucester UK. I played Rugby football internationally as a schoolboy. At the age of 17, a new and wet driving license in my paw, I entered motor racing. I was supported and financed by my parents and so my journey began.

In 1965 I bought a 1293cc Mini-Cooper `S` and campaigned it for a season. Having quickly made some good friends in the racing fraternity, several interesting opportunities came my way. I joined a sports-car team and raced in the Le Mans 24 hours in 1968 and 1969 in a Lola T70. Mechanical failure defeated both efforts. During that period I owned and raced a `D type` Jaguar and an AC Cobra. In those days cars like that were available and not too expensive, now they reside in museums and private collections. I had a chain of interesting cars through my youth including Jaguars, Minis, Mustangs and Lotus-Cortinas.

As a young driver I had my share of accidents too. Often the car would only be worth scrap-metal value by the time I got it home! I worked for an Aston-Martin/Jaguar dealership for a while, which enhanced my experience and gave me the opportunity to sample some very exotic machines, Ferrari, Facel-Vega, Iso and Maserati to recall a few of them.

At the end of 1969 I moved to South Africa to work on my uncle`s farm but the S.A. government had other ideas and drafted me into the army. After five years had passed I was thanked and released from the service. While I was there I bought a beige Cadillac Eldorado, previously the property of Marilyn Monroe. While I was away on a patrol my girlfriend had it re-sprayed pink! I was unimpressed by both the joke and the bill for the work!

When I returned to UK in 1974 I left it behind. On my return I found that the once-mighty British motor industry was in decline and was headed for oblivion. Motor racing was now very expensive so I turned to commercial transport. Driving large trucks gave me freedom and a chance to see some of the world. I don`t remember ever making a career choice but for the next thirty years a truck was my home. For about ten years in that period I owned two trucks of my own.

I also owned a famous MGB-GT, known as `Lucky`. If you`d like to read `The Story of Lucky` there is an article in Inopian`s archive. I finally retired, due to ill-health, in 2008. Since I had varied knowledge and many experiences on our subject I decided to share the stories of the cars I enjoyed (and hated) with the new generation.

Enjoy Inopian… it is constructed and written for you.

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