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).
Carburetter control, fuel mixture economy, and suggestions for improving mileage.
| Identifier | ExFiles\Box 75\2\ scan0251 | |
| Date | 9th August 1921 guessed | |
| Oy2 - G 8621 Sheet #9. to our excellent steering column carburetter control, and to excellent driving, and can only be obtained under touring con-ditions of high speed and well open throttle, and then only by keeping the mixture lever on the weak side the whole time. Ricardo has recently been showing the great economy value of weak mixtures. That and a big spark advance will go a tremendous way towards doubling the mileage as compared with a car which has no mixture control, and only a moderate automatic spark advance arranged for normal mixture full throttle conditions. Add to this our light weight and our high axle ratio, and I think you can explain our good mileage without attempting to invest with any magic properties an induction pipe which has every quality tending towards unsatisfactory distribution with modern fuel, and which proves the possession of these undesirable qualities by crankcase dilution, poor and irregular running after starting, fouled plugs, rapid carbonizing and poor slow speed running. Certainly our constant mixture carburetter and steer-ing column throttle control are about ideal, but I have watched the average driver on a R-R and he has not the slightest idea of using the carburetter control intelligently. Consequently it takes wizards such as yourself or E.P. or R.{Sir Henry Royce} to get these astonish-ing mileage records. The average user appears to leave the mixture lever central, the spark two thirds up, and be content with eight or nine miles to the gallon. A few other cars have some sort of carburation control but only a very crude affair compared with ours. If we can make dynamometer tests on the lines I have suggested above, perhaps we can find something interesting on the subject of fuel consumption. Have you any idea of the fuel air range given by our mixture control? One would say by appearances that it ran from about 9 to 1 strong to about 16 to 1 weak. Enc. (2 photos of L.H. carburetter position) OY. M.{Mr Moon / Mr Moore} Olley | ||