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Adjusting Tappets


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Engine shown is a 2.5 N/A, but the method of adjusting the tappets is the same on most engines that don't have hydraulic tappets. The gap between rocker arm pad and the top of the valve stem is important for several reasons - to allow for expansion of the metal, to ensure that the valve is fully closed when needed, and to ensure the smooth running/timing of the engine.

The rocker cover gasket or oil filler cap leak eventually over a period of time, and the top of the engine gets in a right mess, like the one shown here.


On series and 2.5 N/A or TD engines - remove the filler (series have a 7/16" bolt in the side of the cover to retain the filler)

The heater hoses are held by one of the three acorn nuts that hold the rocker cover on. Remove the centre nut, then slacken the 10mm pinch bolt enough for the pipe support to be removed.



Remove the other two acorn nuts and alloy washers, then the rocker cover will lift away.

The rocker assembly:-


Each tappet should have a locknut and slotted thread - you will need a 13mm ring spanner and blade screwdriver.


Starting at the front of the engine - turn the crankshaft by way of the crank bolt until No2 valve is open. The camshaft lobe for No1 is now out of the way and the tappet for it can be adjusted. Undo the locknut a couple of turns - if the threaded part turns as well, then keep it still with a screwdriver.



Insert the right thickness blade in the gap between the rocker pad and top of the valve stem and turn the tappet thread until the blade is slightly pinched. Keep the screwdriver dead still and tighten the locknut.


You may find that the tappet gap will close too much when you tighten the locknut. If that happens, then re-set the gap, allowing for this. Work through all 8-tappets, making sure that you set the correct gap for the valve - inlet or exhaust. Once done - clean around the top of the head, the gasket faces, and the rocker cover inside and out.

Sticky gaskets are very handy.


Refit the cover, use new alloy washers on the three studs, and re-attach the heater hose clamp.



Les. :)

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