I would get a Haynes manual which goes into detail of how to adjust them. Better still, get a TMF CD, they have got loadsa info on them!
Or see below
idiots guide to "Tightening Tappets"
It will facilitate turning over the engine if the spark plugs are removed at this point. Suitably label the plug leads to ensure they will be reconnected correctly.
The valve adjustments should be made with the engine cold.
The importance of correct rocker arm/valve stem clearances cannot be overstressed as they vitally affect the performance of the engine. If the clearances are set too wide, the efficiency of the engine is reduced as the valves open late and close earlier than was intended. If, on the other hand the clearances are set too close there is a danger that the stems will expand upon heating and not allow the valves to close properly which will cause burning of the valve head and seat, and possible warping.
For this operation the engine can be turned over by engaging reverse gear and pushing the car backwards, or by jacking one of the front wheels clear of the ground and rotating the wheel. In this latter case, top gear should be engaged.
Crankshaft rotation is clockwise, viewed from the radiator end of the engine.
Rotate the crankshaft until each valve in turn listed in the left-hand column below is fully open (spring compressed), then check the clearance of the valve listed opposite in the right-hand column. Valve numbering is from the radiator end of the engine.
Valve No. 1 open check valve No. 8
Valve No. 3 open check valve No. 6
Valve No. 5 open check valve No. 4
Valve No. 2 open check valve No. 7
Valve No. 8 open check valve No. 1
Valve No. 6 open check valve No. 3
Valve No. 4 open check valve No. 5
Valve No. 7 open check valve No. 2
The valve rocker clearance should be 0.012 in (0.305 mm) for both the inlet and exhaust valves (cold). The clearance is correct when the appropriate thickness of feeler gauge is a neat sliding fit between the end of the valve stem and the pad on the rocker arm.
If adjustment is necessary, slacken the adjusting screw locknut with a ring spanner, and turn the adjusting screw on the push rod end of the rocker arm until the correct
Gap is obtained
Turn the screw clockwise to reduce the clearance, or anti-clockwise to increase it. Retighten the locknut while holding the adjusting screw with the screwdriver to prevent it turning, and then recheck the gap.
When adjustment is complete, refit the rocker cover. Use a new cork gasket if necessary.
