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).
Performance graph comparing different valve lift timings and settings against engine RPM.
| Identifier | ExFiles\Box 13\2\ 02-page138 | |
| Date | 9th August 1931 | |
| COMPARISON OF VALVE LIFT 114° SHAFT RM.{William Robotham - Chief Engineer} P.19. LARGE VALVE HEAD. 4.78 C/R 2.0" VALVE THROAT 114° CAMSHAFT E.82448 OPEN EXHAUST TIMING .013 C.L.C.E. TWIN CARBS 14 THROATS I.O. 3° B.T.C. E.O. 54° B.B.C. I.C. 58.1° P.B.C. E.C. 12° P.T.C. HIGH LIFT TIMING .013 C.L.C.E. I.O. 2.25° B.T.C. E.O. 54° B.B.C. I.C. 60.3° P.T.C. E.C. 19° P.T.C. VALVE LIFT .525 VALVE LIFT .470 CLAUDEL HIGH & LOW LIFT B.H.P. B.M.E.P. LBS/SQ' INDUCTION PIPE DEPN R.P.M. HEAD MACHINED TO GIVE A MINIMUM OF .2 CLEARANCE ROUND THE INLET VALVE HEAD. SIMILAR CURVES TAKEN WITH CLAUDEL CARB. SHEWED NO INCREASE IN TOP M.E.P. BUT A SLIGHT DROP IN LOW SPEED M.E.P./2 LBS/SQ' INDUCTION DEPN ROSE .35" HG WITH HIGH LIFT ROCKERS. | ||