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).
Power curves for a 500cc Rudge Unit with a semi-hemispherical head, comparing performance with one versus two exhaust valves.
| Identifier | ExFiles\Box 133\1\ scan0016 | |
| Date | 23th March 1936 guessed | |
| C9 500 cc RUDGE UNIT FIG. VIII POWER CURVES ONE AND TWO EXHAUST VALVES (SEMI-HEMISPHERICAL HEAD) BORE - 3.346" STROKE - 3.464" C.R. 7.3 VALVE TIMING I.O. - 4° E E.O. - 50° E I.C. - 50° L E.C. - 7° L B.M.E.P. (LB / IN²) B.H.P. SPEC. CONS (PT / B.H.P. / HR) PISTON SPEED (FT / MIN) R.P.M. ONE EXHAUST VALVE ONLY TWO EXHAUST VALVES | ||