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).
Recommendations regarding valve spring design and reducing the lift of the exhaust valve.
| Identifier | ExFiles\Box 80\3\ scan0114 | |
| Date | 7th March 1912 guessed | |
| (2) Salters will understand how to make such a spring so that the convolutions come close together when the spring is compressed to its minimum length. As the same gauge of wire throughout the length of the spring will be used, the stress at the bottom may be, say, maximum 50,000 lbs. per sq. in.; at the top it may work out about 56,000. This would be much better than 56,000 throughout. 3. Reduce the lift of the exhaust valve by 1/16" The present springs, I understand, will stand the lift of the inlet (which is 3/8"), and as soon as Hunt is better I want him to set out the exhaust cam so as to get the same time and rapidity and duration of opening and closing as at present, but to lessen the maximum lift by 1/16", which will cause the springs on the exhaust to have the same maximum stress as the inlet. The difference in H.P. through less lift, I imagine will not be perceptible, as it depends so largely on the rapidity and duration of opening, which I do not propose to alter. The reduction of this lift will also enable a slightly increased amount of wire to be used in all the springs and will also reduce the range of stress by quite a material amount. | ||