Jaguar 4.2 Build: The Cylinder Head

One of the most distinguishing features of the Jaguar XK engine is it’s DOHC camshafts which allows for an optimal combustion chamber shape and better flow from the intake to the exhaust. The first step was to get the cylinder head off which corrodes slightly where the aluminum head meets the cast iron block which can be avoided with anticorrosion in fresh antifreeze. After a good clean, work on the valves, seats and stems is critical for the rebuilt. In our case both valve surfaces had to be reground to ensure an optimal seal in the chamber, but the stems were great which is a good sign that the engine has never overheated.

The valve seats were ground with a special stone attached to a canted drill and the valves themselves were reground in the refacer machine. The clearances are set with shims on the top of the valve stem.

Made from aluminum, the cylinder head was fitt onto the cast-iron block while the block was already in the car. It weighed 60 lbs before the valvetrain was fitted so a hoist was necessary with the front hood tilted forward. Hylomar sealer was used to seal the gasket to the block and head and limit corrosion.

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