{"id":8,"date":"2025-02-17T18:59:05","date_gmt":"2025-02-18T00:59:05","guid":{"rendered":"https:\/\/staging.englandengineering.com\/?page_id=8"},"modified":"2025-02-20T20:19:50","modified_gmt":"2025-02-21T02:19:50","slug":"epoch-00","status":"publish","type":"page","link":"https:\/\/xk120.jagnuts.ca\/index.php\/epoch-00\/","title":{"rendered":"The Jaguar XK120"},"content":{"rendered":"\n

What is a Jaguar XK-120?<\/strong><\/p>\n\n\n\n

(A Potted Unofficial History)<\/strong><\/p>\n\n\n\n

The Jaguar XK120 is a sports car manufactured by Jaguar between 1948 and 1954. It was Jaguar’s first sports car had produced following SS 100 production which ended in 1939.<\/p>\n\n\n

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One of the original Aluminium bodied XK-120’s<\/figcaption><\/figure>\n<\/div>\n\n\n

The XK120 was launched in open two-seater (roadster) form at the 1948 London Motor Show as a test bed and show car for the new Jaguar XK engine designed by Jaguar Chief Engineer William Heynes. The display car was the first prototype, chassis number 660001. It looked almost identical to the production cars except that the straight outer pillars of its windscreen were curved on the production version. The sports car caused a sensation at the London Motor show, which persuaded Jaguar founder and Chairman William Lyons to put it into production.<\/p>\n\n\n\n

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The “120” in the name referred to the aluminium car’s 120 mph (193 km\/h) top speed, which was even faster with the windscreen removed; this made the Jaguar XK120 the world’s fastest production car at the time of its launch.<\/p>\n\n\n\n

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Jaguar XK Engine<\/figcaption><\/figure>\n<\/div>\n<\/div>\n\n\n\n
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Open Two Seater<\/figcaption><\/figure>\n<\/div>\n\n\n\n
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Beginning in 1948, the first 242 cars wore wood-framed open 2-seater bodies with aluminium panels. Production switched to the 112 lb. (51 kg) heavier all-steel in early 1950. <\/p>\n\n\n\n

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In 1949 the first production car, chassis number 670003, was delivered to Clark Gable.<\/p>\n\n\n\n

The XK120 was ultimately available in three body styles, all two-seaters and available either as Left (LHD) or Right Hand Drive (RHD): an open two-seater ; a fixed head coup\u00e9 (FHC) from 1951; and a drophead coup\u00e9 (DHC) from 1953.<\/p>\n\n\n\n

Certain Special Equipment roadster and fixed head coupe cars were produced were sold between 1948 and 1949 as an early production build for enthusiasts, denoted by an ‘S’ preceding the chassis number.<\/p>\n\n\n\n

A version with a smaller engine (2-litre 4-cylinder) designated the XK100 and intended for the UK market was cancelled prior to production.<\/p>\n\n\n\n

On 30 May 1949, on the empty Ostend-Jabbeke motorway in Belgium, a prototype XK120 timed by the officials of the Royal Automobile Club of Belgium achieved an average of runs in opposing directions of 132.6 mph with the windscreen replaced by just one small aero screen and a catalogued alternative top gear ratio, and 135 mph with a passenger-side tonneau cover in place. In 1950 and 1951, at Autodrome de Linas-Montlh\u00e9ry, a banked oval track in France, open XK120s averaged over 100 mph for 24 hours and over 130 mph for an hour. In 1952 a fixed-head coup\u00e9 took numerous world records for speed and distance when it averaged 100 mph for a week.<\/p>\n<\/div><\/div>\n\n\n\n

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Fixed Head Coupe<\/figcaption><\/figure>\n<\/div>\n\n\n\n
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XK120s were also highly successful in racing and rallying.<\/p>\n\n\n\n

All Jaguar XK120’s were built in Coventry, England, under the guidance of Jaguar’s founder, William Lyons.<\/p>\n<\/div>\n<\/div>\n\n\n\n

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The first 242 production XK120s were hand-built with aluminium bodies on ash framing and were constructed between late 1948 and early 1950. To meet demand, beginning with the 1950 model year all XK120s were mass-produced with pressed-steel bodies. The aluminium doors, bonnet, and boot lid were retained. The DHC and FHC versions, luxuriously appointed than the constantly exposed OTS cars, and had wind-up windows and wood veneers on the dashboard and interior door caps.<\/p>\n\n\n\n

The XK120’s steel chassis was mostly copied from the Jaguar Mark V, using many of the same parts.<\/p>\n\n\n\n

Most of the early cars were exported.<\/p>\n\n\n\n

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The dual overhead-cam 3.4 L straight-6 XK engine was highly advanced for a mass-produced unit of the time, featuring a high-temperature, high-strength aluminum alloy cylinder head, hemispherical combustion chambers, inclined valves, and twin side-draft SU carburetors. <\/p>\n<\/div>\n\n\n\n

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Drop Head Coupe<\/figcaption><\/figure>\n<\/div>\n\n\n

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Using 80 octane fuel a standard 8:1 compression ratio developed 160 BHP (119 kW). A 7:1 low-compression version with commensurately reduced performance was reserved for the UK market where the post-war austerity measures then in force restricted buyers to 70 octane “Pool Petrol”. The Jaguar factory’s access to 80 octane fuel allowed it to provide cars with the higher compression ratio to the press, enabling journalists to test the model’s optimum performance in Belgium on a long, straight stretch of road between Jabbeke and Ostend.<\/p>\n\n\n\n

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The XK engine’s basic design by produced Jaguar designer William Heynes, and later modified into 3.8 and 4.2-litre versions. The engine was produced by Jaguar in ever more powerful and more efficient forms until 1992.<\/p>\n\n\n\n

All XK120s had independent Heynes designed torsion bar front suspension, semi-elliptic leaf springs at the rear, recirculating ball steering, telescopically adjustable steering column, and all-round 12-inch drum brakes which were prone to fade. Some cars were fitted with Alfin (ALuminium FINned) brake drums to help with brake cooling and overcome the fade.<\/p>\n\n\n\n

The open two-seater provided little weather protection. Its lightweight folding canvas top and detachable side screens stowed out of sight behind the seats. The doors had no external handles; they were opened by an interior pull-cord, accessed through a flap in the side screens when the weather equipment was in place. The windscreen could be removed for aero screens to be fitted.<\/p>\n<\/div>\n<\/div>\n\n\n\n

The drophead coupe; (DHC) had a padded, lined canvas top, which folded onto the rear deck behind the seats when retracted, and roll-up windows with opening quarter lights. The flat glass two-piece windscreen was set in a steel frame that was integrated with the body and painted the same colour.<\/p>\n<\/div><\/div>\n<\/div><\/div>\n<\/div><\/div>\n\n\n\n

Dashboards and door-caps in both the DHC and the closed coupe; (FHC) were wood-veneered, whereas the open cars were leather-trimmed. All models had removable spats (fender skirts) covering the rear wheel arches which enhanced the streamlined look. On cars fitted with optional centre-lock wire wheels (available from 1951), the spats were omitted as they gave insufficient clearance for the chromed, two-eared Rudge-Whitworth knockoff hubs. Chromium-plated wire wheels were optional from 1953. Factory standard 6.00 &times; 16-inch cross ply tyres were fitted on 16 &times; 5K solid wheels (Pre&ndash;1951), with 185VR16 Pirelli Cinturato radial tyres available as a later option.<\/p>\n\n\n\n

In addition to wire wheels, upgrades on the Special Equipment (SE) version included increased power, stiffer suspension, and dual exhaust system.<\/p>\n<\/div><\/div>\n\n\n\n

Engine Specifications<\/p>\n\n\n\n

Configuration :<\/strong> DOHC Straight-6 hemispheric combustion chamber<\/p>\n\n\n\n

Displacement :<\/strong> 3,441 cc (3.4 L; 210.0 cu in)<\/p>\n\n\n\n

Bore \/ Stroke :<\/strong> 83 mm \u00d7 106 mm (3.27 in \u00d7 4.17 in)<\/p>\n\n\n\n

Configurations :<\/strong><\/p>\n\n\n\n