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 chart of high and low lift rockers with twin Zenith carburettors.
| Identifier | WestWitteringFiles\W\September1931-November1931\ Scan029 | |
| Date | 6th October 1931 guessed | |
| R.M.44 COMPARISON OF HIGH & LOW LIFT ROCKERS WITH TWIN ZENITH CARBS. JAPAN UNIT. INLET VALVE DIA 1·4. OPEN EXHAUST 112° CAMSHAFT F.55640. A LIFT ·395 LIFT ·344 COMP RATIO 5·35/1 TIMING TOO EARLY FOR MAX POWER. VALVES SHROUDED BY CYL. HEAD. EX IN .013 CLCE 40 55 4·5 2 B LIFT ·395 LIFT ·344 COMP RATIO 5·15/1 TIMING TOO EARLY FOR MAX POWER. MIN CLCE OF ·225 CUT ROUND INLET VALVE. EX IN .013 CLCE 40 55 4·5 2 C LIFT ·395 LIFT ·344 COMP RATIO 5·15/1 TIMING CORRECT FOR MAX POWER. MIN CLCE OF ·225 ROUND INLET VALVE. EX IN .013 CLCE 46 3·2 10·6 B.H.P. M.E.P. R.P.M. | ||