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 valve overlap with correct timing positions for various engines.
| Identifier | ExFiles\Box 93\5\ scan0008 | |
| Date | 1st October 1934 guessed | |
| H.1523 VALVE OVERLAP WITH CORRECT TIMING POSITIONS SPECTRECodename for Phantom III 2 BOTH INLET CAMS (E.85234) (CAMSHAFT EX: 5042) TIMING .020 CLCE IO T.D.C E.C. T.D.C. BENTLEY (EB.1085) CAMSHAFT (CAM FORMS E.59272) TIMING .020 CLCE IO 3° BTDC EC 8° PTDC 25 HP CAMSHAFT (E.59699) (CAM FORMS E.57174/5) TIMING .020 CLCE IO 1.5° BTDC EC 1.5° PTDC CADILLAC CAMS. CADILLAC (ACTUAL TIMING .020 CLCE) IO 11° PTDC IC 37° PBDC EO - 27.5 BBDC EC 3° BTDC Graph Labels: TDC SPECTRECodename for Phantom III TO LEC &120 INLET OPENINGS VALVE LIFT INS. TDC. CRANK ANGLE EXHAUST CLOSINGS Vertical Axis (Valve Lift): .055, .050, .045, .040, .035, .030, .025, .020, .015, .010, .005 Horizontal Axis (Crank Angle): 45, 40, 35, 30, 25, 20, 15, 10, 5, 0, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55 | ||