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).
Graph comparing the performance of close-centres and standard cylinder heads on a single-cylinder test engine.
| Identifier | ExFiles\Box 133\2\ scan0120 | |
| Date | 1st November 1934 guessed | |
| BENTLEY SINGLE CYLINDER TESTS. SHEET 1 POWER COMPARISON: CLOSE-CENTRES & STD HEADS. "CLOSE-CENTRES" HEAD (L.C.4100), C.R. = 6.35. STANDARD BENTLEY HEAD (F.B.1517), C.R. = 6.4. AEROLITE PISTON. ZENITH TRIPLE DIFFUSER CARBURETTOR (32 1/2% Choke). OPEN EXHAUST. FUEL - DTD 224. BRAKE HORSE POWER B.M.E.P. (LBS/SQ.IN.) FUEL CONS. (PTS/BHP/HR.) R.P.M. STANDARD HEAD, NORMAL TIMING CLOSE-CENTRES HEAD, NORMAL TIMING CLOSE-CENTRES HEAD, VALVES TIMED FOR 3000 RPM (OVERLAP LIMITED TO 12°) | ||