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).
Technical memorandum on the design and performance of valves and valve gear.
| Identifier | ExFiles\Box 181\M11\ img102 | |
| Date | 18th December 1918 | |
| To BY.DA.{Bernard Day - Chassis Design}& EH. from R.{Sir Henry Royce} -3A- R7/C181218 Contd. (1A) VALVES AND VALVE GEAR. The aero type valves with 30º seats, the higher lift cams, and rockers with large rollers, fitted to chassis 7 CA should be included in the new programme. This valve gear seems to be as silent as the old type in spite of its more rapid rate of acceleration. If the more pronounced engine reactions (due to better filling up of cylinders) of the chassis fitted with this valve gear are found to be objectionable, the compression should be reduced slightly. This is a better policy than restricting the entry of the gas into the cylinders, as it is conducive to even running and lack of detonation. Some complaint in pre-War days was made that the large surface valve tappets rotated to new positions and altered the clearance. Mr. Royce considers that the pin preventing rotation could be re-instated in the new tappet, provided it was made a slack fit in the groove and also provided that the tappet spanner was a sufficiently good fit on the tappet to save the pin from shear during adjustments. The valve springs should be of the taper type and strong enough to make the mechanism follow up to an engine speed of 2750 R.P.M. Valves should be of "quick-step" steel instead of Nickel Steel. | ||