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).
Graphs showing the effect of increasing valve clearance on engine performance.
| Identifier | ExFiles\Box 102\1\ scan0040 | |
| Date | 1st January 1940 guessed | |
| R.M. 46 EFFECT OF INCREASING CLEARANCE ROUND INLET VALVE JAPAN OPEN EXHAUST 112° CAMSHAFT E.55640 .344 VALVE LIFT 2 CLAUDELS 26 M/M CHOKES RAMMING PIPES COMPRESSION RATIO 5.35 B.H.P. M.E.P. LBS/SQ.IN. R.P.M. VALVE LIFT .344 EX IN 4-6 2 55 40 .013 CLCE --- MIN. CLEARANCE ROUND INLET VALVE .285" ----- MIN. CLEARANCE ROUND INLET VALVE .166" SEE SKETCH AS ABOVE BUT .395 VALVE LIFT | ||