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).
Tests on various valve lifts and camshafts for 25 HP and 40/50 engines.
| Identifier | Morton\M19\ img074 | |
| Date | 22th May 1931 | |
| To E.{Mr Elliott - Chief Engineer} From Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer}l/KT.22.5.31. X.5771. X.7771. POWER OUTPUT 25 HP. AND 40/50. We are sending you details of the various valve lifts we are trying. The cams we have are - (1) The old short duration. (2) The W.W. long duration reported 20.12.29 and 5.11.29. This has been made in three ways 110,112 and 116° between the cams. and (3) The Expl. long duration camshaft shewn on the attached curve. We have further to test an F.{Mr Friese} engine cam form on the 20 HP. With our existing twin carburetter we find that we get no more power with the C. camshaft, but if we put two Claudel Hobsons on with almost exactly the same induction pipe capacity we get a further 11 HP, i.e. 95 total, for exactly the same induction pipe depression. We shall report on this fully later, but it shews that we have something to learn about ramming at high speeds, and also probably the induction depression which we measure with the 'U' tube does not mean very much. We enclose a blueprint shewing the 20 HP. valve area per litre compared with the existing 40/50, and the 40/50 having an R.{Sir Henry Royce} engine cam. It will be noted that we get a slight increase of lift out of the R.{Sir Henry Royce} engine cam but we do not think that it is sufficient. If it shews promise we shall increase the lift by offsetting the rockers, this being a simple test we can apply to any camshaft. We will get you details of the Zenith downdraught as soon as possible. Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} | ||