Jaguar XK E Type

SCALDED CAT

When the press got their hands on Jaguar’s phenomenal E-type it was the fastest car they had ever tested. For many years after it became the benchmark other cars tried to meet. In the modern world little has changed and still Ferrari and Aston Martin struggle to beat the lithe cat. A race-proven engine and independent rear suspension (IRS) that continued through to the Aston Martin DB7 underpin the dynamics, making an extremely fast car on the road or track.

In this feature we’re concentrating on the XK-engined E-type which came in 3.8 or 4.2-litre guises More than half a century on the car’s performance potential is as deep as your pocket.

BEFORE YOU START .

Many favour the original 3.8-litre engine as a fast revving unit lending itself well to more power. But the 4.2 not only equals the 3.8 but often exceeds it in many areas. The extra 400c did not equate to extra power but it did give more torque.

If the correct blue-style anti-freeze with corrosion inhibitor is used and changed every two-years then most of the XK’s usual troubles will be kept at bay. Both the 3.8 and earlier 4.2 engine blocks are conventional. .However later – so-called long stud block – 4.2 blocks were redesigned and if as new, are the best of all. The studs are longer and pass down into the crankcase area effectively locking the crankcase to the head. However as the studs swim in the coolant neglect leads to corrosion, the studs weaken and sometimes break. The block loses its rigidity and at best the head gasket fails.

At worse the block distorts! Where the earlier blocks are smooth sided the later versions are trimmed with raised sections. A good tip is to look out for a brand new surplus ex-military block; some are in stock with SNG Barratt (http://www.sngbarratt.com).

Before any tuning work is envisaged, its essential to look at some areas which would benefi t even a standard E-type where no performance tuning is intended – namely the cooling and ignition systems.

Contrary to popular belief XK engines aren’t prone to overheating – well not as badly as some suggest. An uprated radiator (try Radtec) offering 25 per cent more efficiency is a wise move along with modern electric cooling fans even for a standard tune engine. Although aluminium radiators play their role the most important thing is to clear the engine block from silt and if you’re contemplating a rebuild then have it chemically cleaned by a specialist.

And while we applaud those who want to keep their cars showroom standard, it’s folly not to fit a modern electronic ignition to maintain distributor performance. There are types that fit neatly under the distributor’s cap and so not to spoil underbonnet appearance if originality concerns you.

COAXING THE CAT

Jaguar had a quoted power figure of 265bhp for both 3.8 and 4.2. But this was back in the brake horse power wars where certain American companies dressed up their figures. Jaguar obtained its readings by stripping the engine of everything likely to drain power so they are hardly realistic figures. The trouble is that any E-type – even a sick one – feels quick. Our advice before coughing up money is to get the car running as best you can in standard form.
The caveat to that would be to change the original points ignition to electronic (as we’ve already stated) and fit high performance plug leads and caps. The originals were fine, reproduction parts are less so, hence the need to change.

A small number of sensible alterations can be done as Jaguar suggested when new in its excellent ‘Tuning & Preparation of E-type Cars for Competition Use’. The recommendations include: ■ Removing standard air-filter assembly
replacing it with mesh covered trumpets and replace needles with SU UO (all available from Burlen Fuel Systems).

• Replace stock exhaust boxes with straight pipes.
• Increase valve clearance from 0.004 (inlet) and 0.006 (exhaust) to 0.008 and 0.010 respectively
• Remove the heater assembly (debatable for road going cars). All part numbers are listed with further suggestions on oils and cooling, all relevant.

Then we urge you spend some time on a rolling road where the engine can be fine tuned to suit the mods. Indeed even standard XK engines benefit from this.

The conventional route to power hikes is usually wild cams and Weber carbs but unless no compromise racing is intended then use this as a last resort. Careful engine preparation is vital with attention to lightening and balancing. The standard rubber bonded crankshaft damper works well enough on road cars but for anything more serious look to a fluid damper but expect to pay around £500.

Jaguars ran comfortably for 24-hours at Le Mans with no conrod failure so standard items work. The finicky can go the Corrillo route if close to £2000 is available. SNG Barratt is marketing Mahle pistons and these seem to be well received. Flywheels can be taken down to 17-19lbs or go radial with a full aluminium alternative but expect to pay large sums which are not really needed for most owners. But do ensure that from crank pulley through to the clutch assembly are completely balanced if you are thinking of a full on rebuild.

Talking of which, you can bore out a 4.2 to 4.5-litre with fair ease for more torque or go even further to 4.7-litre but it gets expensive and not really worth the time, trouble or expense unless you seriously want to compete.

HEAD CASES

Obviously you can have the standard cylinder heads reworked or purchase fully gas flowed types from leading E-type exponents. There is a much cheaper way however and one that’s effective.

The cylinder head as fitted to the fuel- injected 4.2 Series 3 XJ6 already features larger inlet valves as standard and can be harnessed for any XK based engine. This head is extended to the rear with two extra coolant holes. If used on an earlier engine these have to be blocked off. The standard XK camshafts actually work quite well,
although the injection inlet cam should be used if the S3 head is fitted. Attention to porting provides tremendous gains but only if done correctly.

Companies like Sigma Engineering or Rob Beere are excellent but expect a long wait to get your work done.
There are limitations to the standard exhaust manifold and although many companies offer a six-branch, most are decorative. An experiment with Hayward & Scott on a rolling road showed significant gains with its sports system, bhp increasing as extractor manifolds were used.

A recent move is to fuel injection with fully mapped ignition systems has worked well on this engine. The legendary company Mangoletsi has just produced an exquisite dedicated injection inlet manifold ready to accept the various injector systems. This is still in its infancy as cold start and cold running remain issues. We’ll bring you news as soon as everything is sorted but those who have tried similar conversions on XK engines say it brings huge advantages.

For serious track work or racing then options are almost limitless. Those full on Goodwood racers can have engines costing £50,000, fitted with new aluminium engine blocks and-wide angle cylinder heads. But the production parts still work well. Big valve heads and special pistons with 9.5:1 compression ratio will easily handle a trio of 45 DCOE Weber carburettors with the gases exiting via matched length extractor manifolds. Due to the length these route over the engine frames and can cause the bonnet paint to burn off. We would recommend some form of hear resistance. Zircotec will coat the manifolds and depending on colour, can reduce under bonnet temperatures by 60 per cent. An easy 350bhp is attainable with more possible by using going to 4.5-litre.

We reckon the ultimate road engine could actually be the smoothest and we wait in anticipation with fuel injection and mapped systems imminent.

TRANSMISSIONS

Jaguar’s all-synchromesh gearbox is a decent unit but has its limitations of course. Five-speed options are available but have mixed reviews so be absolutely sure what you want before you buy.
Jaguar experimented with a five-speed gearbox and went as far as fitting to a handful of cars. It is possible to fit the later Getrag ‘box as fitted to the XJS, as it will handle the power. Simply Performance (07831 409935) can supply the whole kit.

Other conversions may work but their ability to handle the extra power is doubtful, unless an expensive and dedicated ‘box is used like that from Medatronics in Florida. Realm Engineering can supply the more powerful Toyota Supra gearbox.

An overdrive Jaguar gearbox, say from a Mk2 or S-type cannot be used unless you graft on the transmission tunnel from a 2+2 automatic. And speaking of autos, if you have one, like it but want something better, then the four-speeder as seen in the XK40 can be utilised and it works much better and that added cog improves response.

AT THE REAR

The independent rear suspension remains one of the best around. Radius arms limit front to rear movement by way of slotted rubber bushes. Turning their ‘slot’ to the sides limits movement; for further stiffening uprated bushes are available from most specialists like SNG Barratt.

The ultimate package though has to be the Rob Beere A-frame conversion, where the adjustable rose-jointed radius arms are removed and replaced by Panhard rods with central pick-up points.

Brake improvements go from using the excellent E-type Series 2/420 saloon three-pot callipers from BG Developments to aftermarket four-pot callipers and the option of ventilated discs from the likes of Zeus or Coopercraft. Full on AP Racing aluminium callipers and slotted discs are perfect for the track, regulations permitted. Steering can be quickened by using a fast rack as supplied by SNG Barratt or Rob Beere. Expect to pay from £350 for one.

For the road Polyurethane rack mounts are a vast improvement over the chewing gun consistency originals, but solid mounts are best left for the track.

Replica lightweight E-type aluminium wheels are available from Realm Engineering in either bolt on or peg-drive with a vast option of tyres. Anything over 6-inch diameter rims will require wider wheel arches and in both cases the useless bump stop has to be removed with the mount ground back. FIA cars (where modifications are strictly controlled) are fully catered for by Crosthwaite & Gardiner.

Wheels and tyres are very much a personal choice. Both wire and steel wheels were standard accepting 205 70 VR 15 tyres. If retaining the original rims then there are tyre options from Michelin with the XWX or Pirelli P4000 (although these are currently out of stock). Thinking outside the box, then an alloy wheel option is worth considering.

MWS markets a seven-inch wide16-inch wire wheel in materials including stainless steel. This opens up a whole new sector as a lower profile can be used, from Pirelli PZero to offerings from Bridgestone and Yokohama. Remember that these wheels will be too large to fit the normal spare wheel tray.

But before opening the wallet, ask yourself what you really want. The standard car, tuned right, might well be a surprise!

HEAD CASES

Obviously you can have the standard cylinder heads reworked or purchase fully gas flowed types from leading E-type exponents. There is a much cheaper way however and one that’s effective.

The cylinder head as fitted to the fuel- injected 4.2 Series 3 XJ6 already features larger inlet valves as standard and can be harnessed for any XK based engine. This head is extended to the rear with two extra coolant holes. If used on an earlier engine these have to be blocked off. The standard XK camshafts actually work quite well,
although the injection inlet cam should be used if the S3 head is fitted. Attention to porting provides tremendous gains but only if done correctly.

Companies like Sigma Engineering or Rob Beere are excellent but expect a long wait to get your work done.
There are limitations to the standard exhaust manifold and although many companies offer a six-branch, most are decorative. An experiment with Hayward & Scott on a rolling road showed significant gains with its sports system, bhp increasing as extractor manifolds were used.

A recent move is to fuel injection with fully mapped ignition systems has worked well on this engine. The legendary company Mangoletsi has just produced an exquisite dedicated injection inlet manifold ready to accept the various injector systems. This is still in its infancy as cold start and cold running remain issues. We’ll bring you news as soon as everything is sorted but those who have tried similar conversions on XK engines say it brings huge advantages.

For serious track work or racing then options are almost limitless. Those full on Goodwood racers can have engines costing £50,000, fitted with new aluminium engine blocks and-wide angle cylinder heads. But the production parts still work well. Big valve heads and special pistons with 9.5:1 compression ratio will easily handle a trio of 45 DCOE Weber carburettors with the gases exiting via matched length extractor manifolds. Due to the length these route over the engine frames and can cause the bonnet paint to burn off. We would recommend some form of hear resistance. Zircotec will coat the manifolds and depending on colour, can reduce under bonnet temperatures by 60 per cent. An easy 350bhp is attainable with more possible by using going to 4.5-litre.

We reckon the ultimate road engine could actually be the smoothest and we wait in anticipation with fuel injection and mapped systems imminent.