The engine must only be turned using the normal rotation with an anticlockwise motion begun with the right-hand side of the automobile. Start with the removal of the camshaft cover; then set the engine for TDC on cylinder No 1 which means the inlet and exhaust cam lobes of No 1 cylinder will point upwards so as to enable the checking of the valve clearance. Using feeler blades, gauge the valve lash for the base of the cam lobe to the bucket tappet and document the thickness needed for firm sliding-interference on all of the valves of No 1 cylinder Intake and exhaust clearances differ. Then rotate the crankshaft through 180 degrees clockwise and check and record the four valve clearances for No 3, No 4 and, if necessary, No 2 cylinder. If adjustments are required, the bucket lappets may be altered with the camshafts removed. For small clearances fitting is done using a thin bucket tappet while for large clearances a thick one is fitted using the engraved number on the tappet or a micrometer if the number has worn out. Determine the thickness of the new bucket tappet with the help of the desired and actual clearances, the obtained tappet thickness. The correct thickness should then be obtained and new bucket tappets placed in the cylinder head with replacement of the camshafts. Check that the above clearance has taken its right position, if any of the valve clearances is still out, perform the above steps all over again. A record of the thickness of buckets fitted at each position will help in future modifications, by knowing the clearances and the existing thickness of the bucket that is required, the needed thickness of the bucket can be bought in advance. Last, change the camshaft cover upon confirmation with all its clearances.