From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Design of the 'Seagull' cylinder head, valve rocker gear, and compression ratios.
| Identifier | WestWitteringFiles\J\January1923\ Scan61 | |
| Date | 11th January 1928 | |
| ORIGINAL TO DF. FROM E.{Mr Elliott - Chief Engineer} c. to ej. WCR. HS.{Lord Ernest Hives - Chair} E1/M10.1.23. X9050 X9060 X9070 V38 V3844 X8875 RECEIVED JAN 11 1928 Copy "SEAGULL" CYLINDER HEAD & VALVE ROCKER GEAR. We send you herewith drawings Nos. LeC 1663 and 1667 shewing the above. These drawings give complete information with regard to the cylinder head, and the remainder of the valve gear with the exception of an enlarged drawing of the rocker which we propose to send you, and the shape of the cams, and the strength of the springs. You will notice that this rocker gear has an eccentric adjustment at the centre of the rocker which is intended for use in maintaining the correct clearance at the end of the rocker after the engine has been put into service. The adjustment on the tappet which you already have on LeC 1658 is intended as a Works adjustment for setting in the first instance to cover the various tolerances on the dimensions which affect the valve gear. The rockers are not bushed but are intended to be hardened in the bore as well as on the ends. The eccentric bushes on which the rockers run are also intended to be of steel case-hardened. A double jawed rack spanner is shewn for the rocker adjustment. Referring to the compression ratio for the engine, the design of head we send is primarily intended for a 4 3/4 to 1 ratio, but it is expected that we shall also require a lower ratio, say 4 1/2 to 1, or even 4 to 1, for use when a particularly smooth engine is required. Pistons of 4, 4 1/4, 4 1/2, and 4.75 to 1 should be instructed for test. The dimensions (1) | ||