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).
The performance and suggested improvements for the 'China' 20HP test car before a 10,000-mile trial.
| Identifier | ExFiles\Box 5a\2\ 02-page087 | |
| Date | 5th June 1929 | |
| SECRET. X5840A He. Rv. } FROM R.{Sir Henry Royce} & A.{Mr Adams} DA.{Bernard Day - Chassis Design} } HL/M5.6.29. C. to Sg.{Arthur F. Sidgreaves - MD} LBS. WOT. C. PN.{Mr Northey} CX.{Major Len W. Cox - Advertising Manager} 20HP. 'CHINA' - 3 1/4 BORE. X5840A LEAVING FOR 10,000 MILES X5770 TRIAL IN FRANCE. (1) The specimen brought to WW. yesterday appeared to be a very good car from the short time of driving and riding in it. (2) The engine is especially powerful at low speeds. (3) The speedometer reading is probably 10% high. (4) The Park Ward fabric body struck me as particularly good for silence and lightness, and really, with the other improvements, makes the 20 HP. a distinct success. (5) During the visit of Messrs. Robotham, Lovesay, & Hencock, the following points were discussed: (6) The steering wheel had a thicker rim than SS.{S. Smith}, and the controls were too high: I understand this is not up-to-date. (7) The brakes were smooth and not too sudden - i.e. rather safer than usual. (8) It was agreed that for fast, light cars the back axle ratio might be tried 12/50 instead of 11/50 - (10/47 we consider too low at present). It appeared to get this specimen up to 70 MPH., because until 'Japan' the high speed torque falls off rather quickly after 2000 revs. (9) To improve (8) we might produce a camshaft giving timing like SS.{S. Smith} This could easily be done by :- Using present exhaust as inlet, rapid accelerations. 55 divisions. Making new exhaust 8° longer, rapid acceleration 60 divisions. Angle between 116°: this will be easier for valve springs. Will Mr. Bailey kindly produce this. (10) Somewhere there is a carburetter (original) with larger throttle to which a larger air valve was fitted. This should be tried; the present is too small for the 60 to 70HP. contd. | ||