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2.25 LITRE PETROL AND DIESEL CYLINDER HEAD . Reface valve faces 68. Valves that are satisfactory for further service can be This operation should be carried out using a valve grinding machine. Only from the valve face to avoid thinning of the valve edge. The valve is refaced correctly when all pits are Valve face angles: A . Petrol engine - 30" - Exhaust valve face - 45" - Diesel engine - A I M Lap-in valves 69. To ensure a gas tight seal between the valve necessary to lap-in the appropriate valve to its seat. It is essential keep the valve identified with its seat once the in operation has been completed. that the inlet and exhaust valves in petrol engine have different face angles. 70. Unless the faces to be lapped are in poor condition it should only be necessary to use fine valve lapping paste. Smear a small quantity of on the valve face and lubricate the valve stem with engine oil. 71. Insert the valve in the appropriate guide and using a suction type valve lapping tool employ a light reciprocating action while occasionally lifting the valve off its seat and turning it so that the valve returns to a position on t h e seat. 72. Continue the operation until a continuous matt grey band round valve face is obtained. To check that the lapping operation is off the valve from the valve and scat and make a pencil lines across the valve face. Inset the valve into the guide and while through no further lapping is required. 73. Wash all traces of grinding paste from the valves and cylinder head seats. con tin Assemble valves to cylinder head 74. Insert the inlet valves into the guides and fit new oii seais with the exterior and circuiar spring. Ensure that t h e seal locates in the groove in t h e valve guide. 75. Insert the exhaust valves and fit the oil seals with the ridged exterior and n o spring. continued 39 |