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).
Modifications to increase valve lift for the 25HP 'CHINA' model.
| Identifier | WestWitteringFiles\V\March1931-September1931\ Scan393 | |
| Date | 2nd September 1931 | |
| HS.{Lord Ernest Hives - Chair} ) FROM R.{Sir Henry Royce} & E.{Mr Elliott - Chief Engineer} BY.{R.W. Bailey - Chief Engineer} ) [Struck through] C. to SC. WOR.{Arthur Wormald - General Works Manager} RG.{Mr Rowledge} ['to SC. WOR.{Arthur Wormald - General Works Manager}' is struck through] ORIGINAL [Stamped] R1/M2.9.31. 25HP. 'CHINA' INCREASED VALVE LIFT. x5090. [Handwritten] We do not agree to shifting the centre of the rocker so much as to make the ratio 1.34 instead of 1.2, (1.22 corrected for rocker curvature) for obvious reasons, especially for tappet clearance. You ask for .050" increased lift. The best way to get this is by altering the centre of the rockers .025, and increasing the lift of the cam .030, which gives lift of .314". This would be our best compromise, and will go into the present material. [Handwritten annotation above the previous line]: i.e. 1.255 ratio (corrected) New cam forms will probably be needed. The length between the heavy acceleration .013 clearance is: EX: 61 DIV: --- IN: 57 DIV: The heavy acceleration of the 5% div: inlet cam - Sch. 1153. - equals .003. We now use .004 (at least) to .0045 for car work. Phantom 2. equals .0049 - see LeC. 2918. All this suggests that P. 2. standard valve timing is quite good, so that the low power has never been due to that cause. R.{Sir Henry Royce} [Stamp]: RECEIVED [Stamp]: 1931 SEP 8 | ||