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).
Data tables comparing valve train component specifications and performance characteristics for the 25HP.JAPAN engine.
| Identifier | ExFiles\Box 13\2\ 02-page115 | |
| Date | 27th September 1931 | |
| Top Table: Engine: 25HP.JAPAN Model: P.II. Columns: Wt. of tappet etc. | Tappet spring. | Force on cam at 3000 RPM. | suction of valve. | valve bounce speed. Row 1: 284 lbs | 5 lbs | 5 + 252 = 335 lbs | | 3800 RPM. Row 2: " | " | 5 + 215 = 288 lbs | 31.4 | 3850 RPM. Row 3: " | 10 lbs | 10 + 169 = 254 lbs | " | 4100 RPM. Row 4: " | " | 10 + 140 = 228 lbs | " | 4200 RPM. Row 5: 282 lbs | 10 lbs | 10 + 159 = 236 lbs | " | 4800 RPM. Row 6: " | " | 10 + 133 = 210 lbs | 1.5 lbs | 4950 RPM. Bottom Table: Engine: 25HP.JAPAN Model: P.II. Columns: Wt. of valve & cap. | Wt. of push rod. | Cam-shaft. | Rockers. | At max. accn of valve. | Valve spring. Force. | Force in push rod at 3000 R.P.M. Row 1: .364 | .158 | std. | F.{Mr Friese} | std. | 90 | 72 | 215 Row 2: " | " | " | High Lift F.{Mr Friese} | std. | " | 43.5 | 166 Row 3: " | " | 112º | F.{Mr Friese} High Lift | " | " | 38.5 | 140 Row 4: .17 lbs. | .0875 lbs. | 112º | High Lift | std. | 78 lbs. | 37.5 | 159 Row 5: " | " | std. | " | " | " | 33 lbs | 133 lbs. | ||