CYLINDER HEAD-E.S k INLET VALVE EXHAUST VALVE c tot _I ! I ; 1 -i........ GRAD E15 A B Inlet A-1.530 in to 1.531 in 8-0.3125 in to 0.3175 in C-0.015 in chamfer at 45 (Max.) Exhaust A-1.296 in to 1.297. in 8-0.3125 in to 0.3175 in C-0.015 in chamfer at 45 (Max.) t . F VALVES AND VALVE SEATS \. 0 .1 The valves should be checked in their respective guides for wear and replaced if wear has taken place. (ensure that the wear is in fact on the valve stem and not in the guide bore before replacing the valve). The valve and valve seat faces should be reconditioned in the normal way using specialised equipment or with grinding compound, according to their condition.
A valve seat (hand operated) cutting tool is shown in Fig. E.12. Valves should always be refitted to their original seats and any new valve fitted should be suit- ably marked to identify its position if removed at a later date. (Refer to Fig. E.6 for illustration of valve num- bering) . E16 Material EN32A Case Hardened and Ground Inlet Dimensions A-2.75 in 8-2 in C-0.75 in 0-0.309 in to 0.310 in E-1/16 in at 45 F-1/16 in at 45° G-1/32 in Radius H-1.238 in to 1.239 in J-0.222 in to 0.225 in K-1.523 in to 1.533 in Before refitting the valves it should be ascertained whether the valve head depth relative to the cylinder head face is within the limits given on Page B.2.
This depth can be checked, as shown in Fig. E.13, by placing a straight edge across the face of the cylinder head, then by careful selection of feeler guages mea- suring the distance between the straight edge and the head of the valve. Where vehicle engines have to conform with the smoke density regulation B.S.AU 141a: 1971, then valve depths must not exceed production limits as given on page B.B.
Exhaust Dimensions A-2.75 in 8-2 in C-0.75 in 0-0.309 in to 0.310 in E-1 /1 6 in at 45 ° F-1/16 in at 45° G-1/32 in Radius H-1.018 in to 1.019 in J-0.222 in to 0.225 in K-1.287 in to 1.297 in Where this depth exceeds the maximum limit and even the fitting of a new valve does not reduce this depth below the maximum limit, then the remedy is to fit a valve seat insert as detailed later. When refacing valves or valve seats care should be taken to see that only the minimum amount of metal necessary to obtain a satisfactory seat is removed, and that as narrow a valve seat as possible is maintained.
Hand Grinding After all the valves have been lapped in the valve head depths relative to the cylinder head face should be checked to ensure that they are within the limits given on Page B.B. When grinding or lapping·in valves make certain that all signs of pitting are removed from the seats.