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).
Proposal to reduce engine valve lift, discussing the effects on stress, springs, and valve gear components.
| Identifier | WestWitteringFiles\L\Jan1924-March1924\ Scan23 | |
| Date | 16th January 1924 guessed | |
| (2) By reducing the valve lift to .400," or to be exact .410", the stress range would become the same as 40/50. We propose to do this but also to keep the mean stress and load unaltered so that the valves will then jump at a higher speed than 2500 (74.M.P.H.) e.g. about 2730 (81.M.P.H.) and also the present relation between the valve and valve tappet springs will be retained. We think the engine ought to be able to run up to this speed and that it will most probably do so without touching a period. We are asking Derby to send us models of the moving parts of the valve gear which we have never yet seen, to make sure that there is no excess of weight on these parts, and to confirm that they are using the tubular instead of solid push rods. We should be glad to know if you approve of the proposed new figure for the valve lift, and the proposal regarding the valve spring. As an alternative we could add to the steel in the spring by bulking the valve gear a little. The spring is not bulky at present as can be seen from the attached blue print LeC.1708. We also attach LeC.1709. shewing the tappet spring which has a stress range of 22,000 lbs per sq. in. E.{Mr Elliott - Chief Engineer} | ||