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 comparison graph showing the effect of various inlet valve durations for different cam profiles.
| Identifier | Morton\M19\ img240 | |
| Date | 9th August 1931 guessed | |
| Title: COMPARISON OF VARIOUS INLET VALVE DURATIONS Configuration: 4.78 C/R OPEN EXHAUST STD ALUM HEAD. R.R. TWIN CARBS 1.4" CHOKES 1.8" DIA VALVE THROAT. .013 TAPPET CLEARANCE. Graph Key: Curve A: SCH 1063, VALVE LIFT .490, INLET TIMING 23, 66, EXHAUST TIMING 67, 26. Curve B: LEC 2918, VALVE LIFT .470, INLET TIMING 12, 58, EXHAUST TIMING 68, 3. Curve C: SCH 1093, VALVE LIFT .430, INLET TIMING ?, 54, EXHAUST TIMING 53, 51. Graph Data/Notes: INLET THROAT DIA 1.9 INLET DURATION 272° LEC 2918 241° STANDARD 223° Axes: Vertical Left Axis (B.H.P.): 80 to 170 Vertical Right Axis (M.E.P. LBS/SQ. INS.): 60 to 110 Vertical Right Axis (INDUCTION DEPN. INS. Hg.): 1 to 4 Horizontal Axis (R.P.M): 500 to 3500 | ||