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Large Classic Saloons Register

The JDCA Large Saloons Register covers all the big saloons in the two decades from 1950 to 1970.

Large classic saloons fall into two basic and different production types.  The Chassis cars Mk VII to Mk IX (1950 - 1961) and Monocoque Mk X & 420G (1961 – 1970)

The chassis cars evolved from the earlier Mk V saloon, which inherited its chassis from the prewar SS -Jaguar retrospectively called the Mk IV. Chassis cars have a separate body mounted onto a stiff chassis. All the running gear from the engine through to the rear wheels are attached to the chassis not the body.

The Mk X and 420G are usually referred to as Monocoque, however to be technically correct the term refers to a structural approach that supports loads through an external skin, similar to an egg shell. The word monocoque comes from the Greek for single (mono) and French for shell (coque)

Car bodies are almost never monocoque, most modern cars use unitary construction, (unibody), or Body Frame Integral construction, (BFI) with box sections, bulkheads etc. the skin adds relatively little to the strength or stiffness, other than the floor pan which is made of several components joined to form a stiff platform to attach the upper body parts, of which some form stress or load bearing structures of the overall body shell.

The Mk VII was the first new post WW2 sedan designed entirely in-house at Jaguar. It was originally intended to be the first model to use the now legend XK engine (which continued to power Jaguar cars for over 40 years). Delays in the body pressings meant the engine was ready before the car. So for the launch of the new engine, a prototype two seat sports cars was used, and as fate would have it, the prototype car designated XK 120, was an immediate success. The rest is history and is told elsewhere.

So the Mk VII had to wait another 2 years and was launched to world acclaim in 1950. The saloons cemented William Lyons sales slogan of “Grace Pace and Space” and went on to become the genesis for all Jaguar saloons from then on, with quality build, luxury, high performance, and good value for the money. The early Mk VII and VIIM cars had considerable success in motor sport, on race tracks and road rallies, in the hands of some of the best drivers of the time. 

Below is a brief summery on the Cars and how to identify them. Not all changes are listed, just some the casual observer should notice.

Mk VII (October 1950 to September 1954)
  split 2 part windscreen 
  full one piece spats, flat across the bottom edge
  air vent flaps on each side behind front wheels 
  tri part lamp glasses 
  very small stop-tail lights
  narrow framed radiator grille with winged 3 dimensional growler Jaguar badge.
   Mk VII’s NEVER had a leaper mascot   semaphore turn indicators mounted on the side B pillar
  driving lamps mounted in the front guard below headlights
  drum brakes 
  Unicolour paint.   engine capacity 3.4l    160 bhp @ 5200 rpm and 195 ft/lb torque @ 2500 rpm   twin SU H6 carburettors   101 MPH   fuel consumption 17.6 MPG.

Mk VIIM (October 1954 to July 1957)
  Same as Mk VII but with these changes 
  head lamps single piece glass with a “J” logo in the center
  slightly larger red lens tail lights same as XK 140 
  flashing turn indicators, separate round amber at front, and utilizing the stop lamp at rear. 
  round horn grills replaced the driving lamps which were moved from the below the headlamps to the valance panel directly behind and looking over the front bumper bar.   engine capacity 3.4l   190 bhp @ 5200 rpm and 203 ft/lb torque @ 3000 rpm   twin SU H6 carburettors H8 optional   104 MPH   fuel consumption 18.8 MPG

Mk VIII (October 1956 to December 1959)
 Same as Mk VIIM but with these changes 
  single piece windscreen  cut-away spats with a scalloped bottom edge   chrome trim on both sides starting low on the front guard and looping up then back and running down the waist line contour on both doors and looping down to then form a straight line across the spats to point in line with the rear bumper
  wider and bolder radiator frame with smaller winged Jaguar badge   introduction of the leaper mascot
   two-tone colour on demand   engine capacity 3.4l   210 bhp @ 5500 rpm and 216 ft/lb torque @ 2500 rpm   twin SU HD6 carburettors   106.5 MPH   fuel consumption 17.9 MPG

Mk IX (October 1958 to September 1961)
   Indistinguishable on the outside from the previous Mk VIII except for a rear boot badge.   early Mk IX had the same tail lamps carried over from Mk VIII, however later models had larger tail lights incorporating an amber turn lens on top of the red stop and tail mounted on a chrome plinth similar to the compact Mk II saloon and late XK 150   engine capacity increased to 3.8l   220 bhp @ 5500 rpm and 240 ft/lb torque @ 3000 rpm   twin SU HD6 carburettors   114.3 MPH   fuel consumption 13.5 MPG   disc brakes introduced

Mk X 3.8 (October 1961 to August 1964)
  No chrome trim on the sides
  uniform spacing for the radiator grille 
  dashboard top in timber   unicolour paint   engine capacity 3.8l   265 bhp @ 5500 rpm and 260 ft/lb torque @ 4000 rpm   triple SU HD8 carburettors   119.5 MPH   fuel consumption 13.6 MPG

Mk X 4.2 (October 1964 to December 1966)
  Indistinguishable on the outside to 3.8 Mark X except for the badge on the rear boot lid   engine capacity 4.2l   265 bhp @ 5400 rpm and 283 ft/lb torque @ 4000 rpm   triple SU HD8 carburettors   122.5 MPH   fuel consumption 16 MPG

420G (October 1966 to June 1970)
  body shape unchanged from the Mark X
  chrome trim on the sides with integrated small blinker signals
  radiator grille divided with strong middle bar
  dashboard toped with upholstery and a central clock
  two-tone colour on demand   engine capacity 4.2l   265 bhp @ 5400 rpm and 283 ft/lb torque @ 4000 rpm   triple SU HD8 carburettors   122.1 MPH   fuel consumption 15.8 MPG   note: the short stud version of the 4.2l engine was used until july 1968, after which the long stud variant was used. Cars fitted with the long stud type had the front engine mountings moved from the body shell to the suspension cross member beam. No comparable performance figures between long and short stud versions are available at this time.

(Daimler DS420 )
  for want of a better place to park these limousines the DS420 is included here
  based on the Jaguar Mk X  and produced by Jaguar, it was introduced by British Leyland to provide a replacement limousine after the demise of the Daimler Majestic Major DR450 and Austin Princess. Of the 4981 cars produced, 835 were body less, for custom coach building. As most were bespoke, performance figures are meaningless. It is assumed they were similar but slightly worse than the Mk X Jaguar at their introduction, and development of these cars paralleled approximately those of the Jaguar XJ6 saloons in engines, drivelines and other technical improvements right up to their end in the early 1990s. There are no DS420 cars currently listed in the JDCA Large Saloons Register.

For more detailed descriptions on the various models we recommend Nigel Thorley’s book “Jaguar Mark VII to 420G, The Complete Companion.” Still available (usually 2nd hand) through some specialist bookstores or it can be borrowed by Club Members from the JDCA library.


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