In the early sixties, Jaguar was on a roll having acquired Daimler in 1960 followed by the truck manufacturer, Guy and engine manufacturers, Coventry Climax and Meadows. Robert Couldwell discovers the classics from Jaguar…

It didn’t neglect its own range and to even wider acclaim than the ground breaking XK120 it launched the fabulous E Type in 1961.

This was one of the world’s first 150 mph cars although Jaguar did have to pay special attention to the engines of the road-test cars to achieve the magic ‘150’. Mind you the genuine 145 mph that the production cars recorded was pretty impressive when the average family car could barely crack 75.

It is almost incredible in camera-torn Britain today that back then 145 mph could legally be achieved on any de-restricted single or dual carriageway. Not content with launching the most advanced sports car available, Jaguar went on to launch the luxury limousine, the Mk X in 1962.

This was the final version of a long line of post-war executive saloons which started with the MkV11. Both these new models had some pieces of their design in common – both featured the triple 2 inch carburetor version of Jaguar’s new 3.8 XK engine, as had been fitted to the XK 150S, both had monocoque bodies, replacing the previous models’body on chassis construction, and both featured Jaguar’s newly designed de Dion independent rear suspension mounted in a
separate sub-frame with inboard disc brakes.

This design stood the test of time and was still being used in the mid eighties, its only real disadvantage being brakes barely accessible for servicing. It is a testament to the twinoverhead cam engine designed back in the forties that it could serve both a relatively lightweight 2-seater sports car and a leviathan limousine nearly 17 feet long and 6½ feet wide.

This was down to its inherent smoothness, balance, torque and tractability. The Mk X arguably wasn’t one of William Lyon’s greatest styling achievements with its rather bulbous flanks but its tremendous bulk was quite cleverly disguised and it certainly had road presence making it ideal as a classic ‘limo’.

Jaguar attempted to modernize the interior of the Mk X but there was a lingering feeling that costcutting had taken place and that the luxury, while still evident wasn’t as deep. One benefit was that the interior was more spacious with the rear capable of taking three in real comfort.

For that matter the front could also take three. Thanks to the less raked rear lines the boot was also more commodious, perfectly capable of carrying two sets of golf clubs or luggage for a grand continental tour. The dash board style was lifted from the smaller Mk11 sports saloon and was more logical than the Mk 1X with speedometer and rev-counter directly in front of the driver.

This was a heavy car at around two tons and when fully laden with five or six adults and their luggage the 3.8 engine was proving only to be just adequate. It took Jaguar 3 years to deal with this and they launched the 4.2 litre version in October 1964 for the 1965 model year. The new unit lost a little in smoothness, the natural result of enlarging engines but fortunately the cabin was so well insulated that it wasn’t obvious.

What did stand out was the extra torque up from 260 lbs/ft to an impressive 283. This was enough to increase the maximum speed from 114 mph to around 125 mph with improved acceleration particularly in the mid-range.

A new, much improved allsynchromesh gearbox was fitted although most Mk Xs were specified with the uprated Borg Warner model B automatic box. An alternator replaced the dynamo of the 3.8 and power steering and braking systems were improved. Air conditioning became available as an option in 1966.

In 1967 the whole Jaguar range was upgraded and the Mk X became the 420G with various cosmetic changes sufficient to keep the car fresh and desirable as competition was increasing. The grille now had a central vertical bar, there were chrome strips on the flanks, repeater indicators on the front wings and the option of two-tone paint. Safety was becoming an issue and a black padded roll was added to the top of the dashboard. The seat leather was now perforated.

Jaguar’s new range offered 3 saloon body shapes, the 240/340, which were the cost-cutting, rationalised replacements for the Mk 11 2.4, 3.4 and 3.8, the independent rear suspension 420 and the 420 G luxury car. The 420G became the only survivor of that range of cars, the rest of which were killed off after the launch of the XJ6 in 1968. Production of the 420G actually continued well into 1970.

As usual with large saloons it is not worth buying anything other than a pristine, road worthy example. While a rough car can be bought for £1,000 the restoration cost would be anything up to £80,000. Fortunately, good cars are available for around £10,000 and at that price should only require ongoing ma intenance which apart from those dreaded inboard brakes is very straightforward with a huge range of mechanical service and repair parts available from several suppliers.

The Mk X is a very much more modern car to drive than the previous Mk 1X with much less roll on corners. The steering and automatic gearbox are more responsive and the brakes more reassuring. It is a wide car which could be problematic where accessibility is limited but overall it will be a very satisfying car for both driver and paying passenger.

As personal transport it will still be highly capable of relaxed and rapid continental trips with easy 100 mph cruising where allowed.

What to look for:

Engine: The Mk X engine like its predecesors is as bomb-proof as it gets and properly re-built will last for 100,000 miles plus with little trouble providing that normal maintenance has been carried out. You should expect some tappet noise particularly when cold and should be suspicious if it is absent as this suggests the tappets require re-shimming to correct the clearances. If not properly maintained with the correct corrosion inhibitors, sludge in the radiator can cause overheating and subsequent head gasket failure. The XK engine was never particularly oiltight and leaks can be expected from the rear crankshaft oil seal which can now be upgraded to a better material. Oil pressure should be 20 lbs+ at tick over and 40 lbs+ at normal cruising speeds. The later 4.2 engine has similar longevity. Good quality complete re-builds cost from £2,000 and can include simple tuning to give more power and importantly more torque.

Gearbox: The Moss manual gearbox fitted to the 3.8 models is somewhat agricultural and requires patience to achieve smooth changes. It is however extremely rugged. The later all-synchromesh Jaguar unit of the 4.2 engined model is a much better box and can be retrospectively fitted to 3.8 cars as can various modern 5 speed boxes such as Borg Warner and ZF. The optional automatic is long lasting and having been fitted to many cars of this period has good parts availability with lots of specialist support.

Brakes: The all round disc brakes work well when properly maintained which is something to look for when buying because of those in board rear discs which don’t always receive the routine maintenance they need.

Bodywork: Of monocoque construction with no chassis the structure becomes much more important and the cost-saving manufacturing process does provide lots of opportunities for rusting. It is absolutely essential to take a Jaguar specialist when buying. Once a rust free car has been purchased the underside should be heavily doused with Waxoyl or other similar oxygenexcluding product.

General: The huge advantage with these wonderful old ‘sports – limos’ is that because many of their components are shared with prolific and desirable Jaguar sports cars, pretty well everything is available from several different parts specialists. Even some body panels are available.