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 engine configurations with different valve lift timings and a machined head.
| Identifier | Morton\M19\ img238 | |
| Date | 9th August 1931 | |
| COMPARISON OF VALVE LIFT 114° SHAFT R.M. P.19 LARGE VALVE HEAD 4.78 C/R 2.0" VALVE THROAT 114° CAMSHAFT ROCKER RATIO STANDARD TIMING ON C.L.C.E. TWIN CARBS I.O. 13° B.T.C. E.O. 56.5° B.B.C. I.C. 58.5° P.B.C E.C. 12° P.T.C. HIGH LIFT TIMING ON C.L.C.E. I.O. 24-25° B.T.C. E.O. 54° B.B.C. I.C. 62° P.B.C. E.C. 18° P.T.C. VALVE LIFT .525 VALVE LIFT .470 CLAUDEL HIGH & LOW LIFT HEAD MACHINED TO GIVE A MINIMUM OF .2" CLEARANCE ROUND THE INLET VALVE HEAD. R.P.M. INDUCTION PIPE B.M.E.P. LBS/SQ" 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 lbs WITH High Lift Rocker. | ||