This blog, in addition to the usual maintenance details for classic mini cars, an attempt is made to explain the "whys" and "wherefores" of the various jobs.

Saturday, 17 October 2009

Removing the Cylinder Head

Drain the cooling system and disconnect the battery cable at the positive terminal post in order to prevent the

Fig. 22. The cylinder-head nuts must always be slackened and tightened in the order shown. A similar sequence should be followed when an 11-stud head is fitted

possibility of any "shorts." Disconnect the sparking plug leads and number each cable to avoid confusion on reassembly. At this stage it is advisable to remove the sparking plugs, putting them aside for cleaning and resetting of the gaps.

Remove the air cleaner and disconnect the carburettor controls and the petrol pipe and vacuum pipe to the distributor. The carburettor or carburettors may now be removed.

Slacken the securing clips and remove the radiator hose and heater hoses, if fitted. Slacken the clip on the water by-pass hose, beneath the thermostat housing and disconnect the radiator tie-plate.

Slacken the nut securing the exhaust pipe clamp to the manifold and release the clamp. The manifold securing nuts can now be removed and the manifold taken off.

Attention should next be turned to the valve rocker shaft assembly. Remove the rocker cover from the top of the cylinder head and unscrew the nuts that retain the rocker shaft brackets; slacken each nut gradually, a turn at a time, and at the same time slacken the five external cylinder head nuts, following the sequence shown in Fig. 22. This is most important, to avoid distorting the head.

The rocker assembly can now be lifted off and the eight push-rods that operate the rockers withdrawn, one at a time, and laid out in order in a place where they are not likely to be disturbed, so that they can be refitted in their original positions when the engine is reassembled. Never allow the rods to be mixed; in service, the ball-ends and cups on the rods become lapped to the tappets and rocker screws with which they mate.

If the head does not come away easily, do not attempt to prise it up by inserting a screwdriver or similar tool between the head and the block, as this may damage the machined surfaces. A sharp tap with a wooden mallet, or with a hammer on a block of wood held against the side of the head, should free the joint.