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).
Comparative table of valve train specifications for 25HP Japan and Phantom II engines.
| Identifier | ExFiles\Box 102\5\ scan0053 | |
| Date | 12th May 1931 guessed | |
| First Table: | Engine. | Wt. of valve & cap. | Wt. of push rod. | Cam-shaft. | Rockers. | At max. accn of valve. | Force in push rod at 3000 R.P.M. | |---------------|---------------------|------------------|------------|------------|------------------------|------------------------------------| | | | | | | Valve spring. | Acc. Force. | | | 25HP. JAPAN. | .17 lbs. | .0875 lbs. | 112° | std. | 78 lbs. | 33 lbs | 133 lbs. | | " | " | " | 112° | High Lift | " | 37.5 | 159 " | | " | .415 | " | F.{Mr Friese} | std. | " | 38.5 | 140 " | | " | " | " | F.{Mr Friese} | High Lift | " | 43.5 | 166 " | | P.II. | .364 | .158 | std. | std. | 90 | 72 | 215 | | " | " | " | R.{Sir Henry Royce} | " | " | 100 | 252 | .0795 Second Table: | Engine. | Wt. of tappet etc. | Tappet spring. | Force on cam at 3000 RPM | Suction of valve. | Valve bounce speed. | |---------------|--------------------|----------------|------------------------------|-------------------|---------------------| | 25HP. JAPAN. | .282 lbs. | 10 lbs. | 10 + 133 + 67 = 210 lbs. | 15 lbs. | 4950 RPM. | | " | " | " | 10 + 159 + 67 = 236 lbs | " | 4800 RPM. | | " | " | " | 10 + 140 + 78 = 228 lbs | " | 4200 RPM. | | " | " | " | 10 + 166 + 78 = 254 lbs | " | 4100 RPM. | | P.II. | .284 lbs | 5 lbs | 5 + 215 + 68 = 288 lbs | 31.4 | 3850 RPM. | | " | " | " | 5 + 252 + 78 = 335 lbs | " | 3300 RPM. | Vertical text on right margin: P5090. | ||