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 and timing positions for various engines.
| Identifier | ExFiles\Box 85\3\ scan0027 | |
| Date | 30th June 1934 guessed | |
| H=1523 VALVE OVERLAP WITH CORRECT TIMING POSITIONS SPECTRECodename for Phantom III 2 BOTH INLET CAMS (E.85234) (CAMSHAFT EX.15042) TIMING .020 CLCE IO T.D.C EC 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. SPECTRECodename for Phantom III TO LEC. 4120 CADILLAC (ACTUAL TIMING .020 CLCE) IO 11° PTDC EO 27.5 BBDC IC 37° PBDC EC 3° BTDC INLET OPENINGS EXHAUST CLOSINGS TDC .055 .050 .045 .040 .035 .030 .025 .020 .015 VALVE LIFT -INS .010 .005 TDC CRANK ANGLE | ||