Preliminary test results for a larger choke carburetter on a 20/25HP car.
| Identifier | ExFiles\Box 102\1\ scan0071 | |
| Date | 15th January 1932 | |
| For Files. Y5080. 15. 1. 32. 20/25HP. CAR LARGER CHOKE CARBURETTER. We have carried out preliminary tests on 19.G.IV. fitted with a standard carburetter modified by using 50% larger chokes and a throttle edge slow running device. Two alternative air valves were available, light standard and heavy. Performance tests were taken over the usual hills, great care being taken that in each case the carburetter setting was the best obtainable for power output. The results obtained are as follows, the larger choke carburetter fitted with light or heavy air valve being indicated as so many seconds better or worse, than the standard carburetter. Stanton Hill. Light air valve: equal. Heavy air valve ½sec. worse. Ticknall Hill. Light air valve: -1½secs. worse. Heavy air valve 3½secs. worse. Pistern Hill. Light air valve: -2secs. worse. Heavy air valve 6secs. worse. The decrease in power is not shown up as being at any particular point in the speed range but appears general. No high speed tests have been carried out: in view of the drop of power at the lower speeds it was assumed that any possible small increase at top speed was not worth having. General Behaviour. (a) Light air valve. The carburation being the best power setting, was quite good throughout the speed range at full throttle, a distinct response to the carburation lever took place at any speed and to an approximately equal degree. No flat spots were present. The bad feature of the carburation is its excessive richness when idling at speeds up to the equivalent of approx 30 m.p.h. If this is corrected by reducing the low speed jet, loss of power is at once apparent together with a very flat spot at low speeds 5 to 6 m.p.h. full throttle. No attempt was made to correct the richness by altering the throttle edge slow running device. | ||
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).