XK six or V12

The E-Type ran with two engine families. Series 1, 1.5 and 2 used the twin-cam XK six in 3.8 and 4.2-litre form, covered in detail on the XK engine page. Series 3, from 1971, used the 5.3-litre V12. The difference is not simply more cylinders. The cars around the engines were aimed at different drivers, and they feel it.

Character on the road

The XK six is the sportier of the two. It is a long-stroke twin-cam with real induction noise, it responds sharply once warm, and the 4.2 in particular pulls strongly from low revs. The car feels lighter at the front than the V12 does, and the steering reflects that.

The V12 is smoother than the six by a wide margin, quieter at a cruise, and almost entirely free of vibration. Series 3 is longer, wider tracked and heavier, with power steering standard on most cars and automatic transmission common. It is a fast tourer. Owners who expect the sharpness of a Series 1 roadster are usually disappointed, and owners who wanted a car for six-hour drives usually are not.

Servicing and the week-to-week

On the six, most routine work is reachable. Valve clearances are set by shim, which is a slow job rather than a difficult one. Three SU carburettors, or two Zenith-Strombergs on later American cars, can be balanced by an owner with patience and the right gauge. Ignition is simple on all but the last cars.

On the V12, everything is doubled and access is tighter. Four carburettors on carburetted cars need balancing as a set, ignition on early Series 3 cars means twelve plugs and one distributor with a great deal to do, and the plugs themselves are awkward to reach. None of this is exotic work. It simply takes longer, which matters if you are paying someone by the hour.

Cooling, the honest difference

The single most repeated V12 ownership issue is heat. The engine bay is full, the radiator has limited spare capacity, and a system that is merely acceptable will cope in motion and struggle in traffic. Owners who take the cooling system seriously, meaning a correct radiator, a healthy pump, the right thermostat and working fans, generally report the engine as dependable.

The six is more tolerant, and not immune. A blocked core or a slipping fan belt will overheat any E-Type. The difference is the size of the margin before it does.

Parts and support

Both engines are supported by an active specialist trade, and service items for either are readily obtainable. Where the picture is less even:

• Six-cylinder cars. Very well supported overall. The pinch points are early 3.8-specific parts, Moss gearbox internals, and trim or brightwork unique to the first years of production.
• V12 cars. Engine and running-gear parts are well supported. The awkward items tend to be Series 3-specific ancillaries, emissions-related components on late American cars, and some electrical parts.
• Both. Body panels and structural sections are available, and their fit and quality vary enough that specialists routinely fettle them. That is a restoration question rather than an engine question, and it is covered on the restoration page.

This archive does not name or rank suppliers, and it does not carry advertising. Owners' clubs are the reliable route to current advice on who is supplying what.

Running costs, in general terms

Precise figures are not something this archive will invent, because they depend on the car, the country and who does the work. What can be said with confidence is directional. The V12 uses noticeably more fuel than the six. It carries more consumables: twelve plugs, more coolant, more oil, and more of everything at a service. Labour hours are higher for the same operation because access is worse. The six is the cheaper engine to run, and neither car is cheap.

Common questions