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).
Design for modified rockers for the Wraith III engine, detailing changes to achieve a .350 valve lift.
| Identifier | ExFiles\Box 10\3\ 03-page136 | |
| Date | 31th August 1937 | |
| E-C-D-9 VALVE LIFT CALCULATIONS SINE L/2 = .1375 / 1.200 = .11458 ie. L/2 = 6° 34' 14.5" L = 13° 8' 29" SINE L = .22735 COS L = .97381 H = 1.500 X .22735 = .34102" A = .625 X .97381 = .60862" B = .625 - .60862 = .01638" VALVE LIFT = .34102 + .01638 = .3574-0" CAM LIFT = .275 (BASE CIRCLE = .350.) ROCKER RATIO 1.550/1.200 = 1.280/1.000 ROCKER BUSH LOCATED BY TAPER PIN AS ON PH. II SECTION AA{D. Abbot-Anderson} THE PHANTOMED LUBRICATION SCHEME IS INCORPORATED IN THE NEW ROCKERS & THE SIZES OF THE OIL DRILLINGS ARE TO RM{William Robotham - Chief Engineer} 386/4 USE EXISTING PUSH ROD THE CENTRED VALVE GUIDE WITH SERVANT DELETED WILL BE SHOWN ON A LATER DESIGN, AS THIS DRAWING IS ONLY INTENDED TO SHOW THE MODIFICATIONS NECESSARY FOR ALTERED VALVE LIFT ON AN EXISTING ENGINE. STUD UNALTERED APART FROM THE MODIFIED OIL DRILLINGS & THE OFFSET STUD HOLES, THE ROCKER SHAFT IS UNALTERED. THE ROCKER PEDESTALS ARE MODIFIED AS SHOWN. .050 SEAT WEAR FOR GRINDING INSTRUCTIONS SEE LEC'S S543-S504 NOT SUITABLE FOR PRODUCTION IF IT IS DECIDED LATER TO ADOPT THIS ROCKER RATIO, THE ROCKER PEDESTALS SHOULD BE MADE CENTRAL WITH ROCKER SHAFT & THE FACINGS ON CYLINDER HEAD ALONG WITH THUMB NUT BOSSES ON ROCKER COVER SHOULD BE ALTERED TO SUIT. PLEASE NOTE. THE CYLINDER HEAD IS NOT ALTERED. ROLLS-ROYCE LTD. AUG 31 1937 DERBY MODIFIED ROCKERS (.350 VALVE LIFT) WRAITH III FS{F. Steele}/18/4 FOR FURTHER PARTICULARS SEE LEC's S543 & S504 | ||