Cylinder head - removal and refitting
Removal
1 If the engine is in the vehicle, carry out the preliminary operations described in paragraphs 2 to 15.
2 Open the bonnet and fit protective covers to the front wing upper surfaces.
3 Disconnect the battery earth strap. It is as well to remove the battery, so that no metal objects are placed across its terminals.
4 Remove the air cleaner unit.
5 Drain the cooling system. Note that the coolant should have an antifreeze solution mix and can be used again, so drain into a suitable container for re-use.
6 Disconnect the hoses from the thermostat housing.
7 Detach the choke cable.
8 Release the throttle cable from the carburettor operating lever by moving the spring clip and removing the bracket fixing bolt.
Disconnect the throttle cable and bracket
9 Disconnect the fuel and vacuum pipes from the carburettor.
10 Disconnect the breather hose from the inlet manifold.
11 On vehicles with servo-assisted brakes, disconnect the vacuum hose from the inlet manifold.
12 Disconnect the HT leads from the spark plugs.
13 Disconnect the electrical leads from the temperature sender unit, inlet manifold, carburettor and radiator fan thermal switch.
14 Unbolt and remove the heated air box from the exhaust manifold (where fitted).
Heated air box on exhaust manifold
15 Disconnect the exhaust downpipe from the manifold by unbolting the connecting flanges. Support the exhaust system at the front end.
16 Pull free and remove the oil filler cap with breather hoses.
17 Extract the four screws and remove the rocker cover.
18 Unscrew and remove the four fixing bolts and lift away the rocker shaft assembly from the cylinder head.
19 Withdraw the pushrods, keeping them in their originally fitted sequence. A simple way to do this is to punch holes in a piece of card and number them 1 to 8 from the thermostat housing end of the cylinder head.
Withdraw the pushrods
20 Remove the spark plugs.
21 Unscrew the cylinder head bolts progressively in the reverse order to that given for tightening. Remove the cylinder head.
Refitting
Caution: Never use jointing compound when refitting the cylinder head and gasket.
22 Before refitting the cylinder head, remove every particle of carbon, old gasket and dirt from the mating surfaces of the cylinder head and block. Do not let the removed material drop into the cylinder bores or waterways: if it does, remove it. Normally, when a cylinder head is removed, the head is decarbonised and the valves ground in to remove all traces of carbon.
23 Clean the threads of the cylinder head bolts and mop out oil from the bolt holes in the cylinder block. In extreme cases, screwing a bolt into an oil-filled hole can cause the block to fracture due to hydraulic pressure.
24 If there is any doubt about the condition of the inlet or exhaust gaskets, unbolt the manifolds and fit new ones to perfectly clean mating surfaces.
25 Locate a new cylinder head gasket on the cylinder block, making quite sure that the bolt holes, coolant passages and lubrication holes are correctly aligned.
26 Lower the cylinder head carefully into position on the block.
27 Screw in all the bolts finger tight and then tighten them in four stages, in the sequence shown
Cylinder head bolt tightening sequence
to the specified torque.
28 Refit the pushrods in their original order.
29 Lower the rocker shaft assembly into position, making sure that the rocker adjusting screws engage in the sockets at the ends of the pushrods.
Refit the rocker shaft assembly - engaging the adjuster balls into the
pushrod caps (sockets)
30 Screw in the rocker pedestal bolts finger tight. At this stage, some of the rocker arms will be applying pressure to the ends of the valve stems and some of the rocker pedestals will not be in contact with the cylinder head. The pedestals will be pulled down, however, when the bolts are tightened to the specified torque, which should now be done.
31 Adjust the valve clearances.
32 Refit the rocker cover. If the gasket is in anything but perfect condition, renew it.
33 Fit the oil filler cap and breather hose and the spark plugs. Tighten these to the specified torque. They are of tapered seat type, no sealing washers being used.
34 Connect the exhaust downpipe and fit the heated air box.
35 Reconnect all electrical leads, vacuum and coolant hoses.
36 Reconnect the cables. Refit the battery (if removed) and reconnect the battery terminals.
37 Fit the air cleaner.
38 Refill the cooling system.