Jaguar S-type and 420 Buying Guide

The Jaguar S-type and 420 are cheaper alternatives to the MkII, and they’re also arguably better cars – which is why they’re worth a closer look

Jaguar S-type and 420 Buying Guide

How much to pay

• Project £2000-6000 • Good £10,000-15,500 • Concours £18,000-28,750 •

Overview

Practicality ★★★★
Running costs ★★★
Spares ★★★★
DIY friendly ★★★
Investment ★★★
Desirability ★★★

Fancy a Jaguar MkII but can’t afford one? Well you’re in luck, because in 1963 the marque launched an updated MkII called the S-type. This had most of the glamour of its stablemate, but also boasted an improved interior, better handling (thanks to the fitment of the MkX’s independent rear suspension) and a larger boot. Originally sold alongside the MkII rather than replacing it, the S-type is now significantly cheaper than its higher-profile sibling – even though it cost more when new.

The S-type came with a 3.4 or 3.8-litre version of Jaguar’s legendary XK engine, but from 1966 there was a 4.2-litre edition known as the 420. The same car as the S-type but with a bigger engine plus a restyled nose, the 420 sold alongside the MkII as well as the S-type. As if this wasn’t enough, there was also a Daimler take on the 420 (the Sovereign) – and that was not to be confused with the 420G, the updated version of the Jaguar MkX rather than the MkII. No wonder buyers were confused…

Your AutoClassics Jaguar S-type inspection checklist

Engine

Offered in 3.4 or 3.8-litre forms (S-type) or 4.2-litre (420), the XK engine needs regular maintenance or it’ll wear prematurely. Ensure the unit doesn’t sound hollow or rattly, and that the oil is clean; budget for a rebuild if the engine shows signs of wear. Put this off and you’ll end up paying a lot more, particularly if something breaks.

The XK powerplant has a cast-iron block and alloy cylinder head; because of the latter, anti-freeze levels must be maintained to stave off internal corrosion. A healthy engine will show 40psi of oil pressure at 2500rpm, but senders and gauges often under-read. Expect some oil consumption, but lots of smoke on the over-run points to hardened valve-stem seals or worn valve guides.

While the XK engine can be made oil-tight, do expect some weeping. If the underside is coated in gunk the rear crankshaft oil seal has probably failed, which means a complete rebuild is due. Parts availability for the XK engine is excellent, and there are plenty of specialists that will do the work for you. There’s also a raft of upgrades available – but the costs can add up very quickly.

Gearbox

Until September 1965, manual S-types featured a four-speed Moss transmission without synchromesh on first. It’s a strong unit, but on hard-driven, abused or high-mileage cars you should expect some wear. The problem is that parts for this gearbox are scarce, so rebuilds are very costly.

Later S-types and all 420s came with an all-synchro ’box that’s strong but is now much harder to find on a used basis, so whatever is fitted make sure it doesn’t jump out of gear and that you can select ratios easily. It’s possible to convert to a modern Borg-Warner five-speed manual trans, but it’s a very costly exercise.

Overdrive was optional for all S-type and 420 derivatives, and most cars came with it. This Laycock system should engage smoothly and swiftly; any issues are likely to be down to clogged filters or dodgy electrical connections. It’s unlikely that a rebuilt overdrive will be needed, but they are available on an exchange basis.

Also check for clutch slippage, because fitting a new one means removing the engine. However, most S-types and 420s have a Borg-Warner automatic gearbox. A DG unit was fitted until June 1965; after that there was a type 35 unit. Both are very durable, but the latter is smoother. Rebuilds are rarely needed, with the DG and type 35 units being interchangeable.

Suspension and brakes

Neither the S-type nor the 420 got power steering as standard, although it was a popular option – and it’s quite necessary with the weight of that big straight-six in the nose. Earlier power steering featured a Burman recirculating-ball system, which is low-geared but reliable. Later cars got a higher-ratio Adwest set-up, which had a lot more feel.

One of the key characteristics that separated the S-type from the MkII was the fitment of independent suspension all round; it’s the same set-up as was used on the Mk10 and E-type. As such it’s reliable, but you still need to check for the usual potential issues such as tired dampers, worn bushes and sagging springs. Everything is available and upgrades are easy.

As with the MkII, the S-type and 420 came with disc brakes all round. However, even in good condition the system is only just up to the job, while the 420 benefited from having different front uprights and larger three-pot calipers. The problem is usually down to corroded pistons and cylinders; be especially wary of cars that have been standing or have been used only very sparingly. Everything is available and upgrades are straightforward, but parts costs are high despite the system being relatively simple.

Bodywork

Unsurprisingly, weakened bodyshells are the main cause of S-types being scrapped. The MkI (which evolved into the MkII, then the S-type) was Jaguar’s first monocoque model, so its structure incorporates numerous rust traps. It doesn’t help that Jaguar applied virtually no rust-prevention measures.

Take on a baggy S-type and you’ll need a lot of expertise – plus a well equipped workshop – to revive it. Get it restored professionally and it’ll cost you far more than to simply buy a decent example at the outset – and much more than the car will be worth in the foreseeable future.

If there’s much visible corrosion there’ll be far more hidden in the structure – an S-type that looks superficially good can be rotten underneath, so get the car on a ramp. Start with the two longitudinal chassis legs, which meet a crossmember beneath the nose. Although the structure is unitary, this integral chassis adds essential strength.

Also focus on the area where the chassis legs join the crossmember and the adjacent ‘crows feet’, which tie the front wings to the crossmember. These are the supports for the front wings, along with the vertical radiator cowls. Expect rust here, allowing water into the chassis leg. Corrosion then moves down to the jacking point below the A-post, so look for distortion of the metal and poor-quality plating. This complicated-to-repair area is often bodged.

Check the base of each front wing, looking for cracked paint working downwards across the sill from the bottom front corner of the door aperture. This area is key, as proper restoration requires a jig for strengthening and all rotten metal to be cut out. The usual giveaway is uneven door shuts, with the lower front corner sticking out while the window surround is in contact with the door jamb.

Other rot spots include the rear anti-roll bar mountings, floorpans, wheelarches and back of the sills, along with the spare wheel well’s centre section and fuel tanks (there are two). That’s not all, though; the outer panels also corrode spectacularly, especially the grille and headlight surrounds, plus the area where the sill and front door meet, along with the junction of the rear door and wheel-spat. The trailing edge of the boot lid also rusts, as do the door bottoms.

Interior

A 1960s Jaguar interior is something to behold if in good nick, thanks to all that wood and leather. However, the marque didn’t use the best-quality materials, so tired trim is common. You can buy some superb trim kits to make it all as good as new, but by the time you’ve replaced the carpets, seat covers, trim panels and headlining you’ll have spent plenty. Get it all done by a specialist and you’ll have to find another hefty chunk of change.

History

  • 1963: S-type debuts, with 3.4 or 3.8-litre XK engines and manual or auto transmissions. The 3.8 gets a limited-slip diff.
  • 1964: All-synchro gearbox is now available as an option.
  • 1965: All-synchro gearbox is now standard, while a bigger servo means stronger brakes.
  • 1966: Jaguar 420 (and Daimler Sovereign) goes on sale with a 4.2-litre engine and restyled nose.
  • 1967: Facelift means the S-type’s foglamps disappear and there’s now Ambla trim instead of leather.
  • 1968: Final S-types and 420s are made, but the last Daimler Sovereign isn’t built until 1969.

AutoClassics says…

You don’t have to be on a budget to fancy an S-type or 420 over a MkII, as these overlooked models are superior in various ways. However, if buying a MkII is fraught with danger, trying to find a decent S-type or 420 is even more so, as decent examples are even rarer.

Total production for the S-type ran to 9928 examples of the 3.4, and 15,065 3.8 models. Meanwhile, 10,236 420s were made, along with 5824 Sovereigns – so these cars aren’t super rare as such. Good survivors aren’t common, though, which is why you absolutely must buy the best you can afford and the best you can find.

Specifications

S-type 3.4
  Power 210bhp
  Top speed 119mph
  0-60mph 13.9sec
  Economy 16mpg

S-type 3.8
  Power 220bhp
  Top speed 121mph
  0-60mph 10.2
  Economy 15mpg

420/Sovereign
  Power 245bhp
  Top speed 123mph
  0-60mph 9.9sec
  Economy 15mpg

Picture courtesy of Andy McCandlish

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