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).
Bentley carburation issues and the testing of experimental needles to improve snap acceleration.
| Identifier | ExFiles\Box 31\5\ Scan261 | |
| Date | 19th November 1934 | |
| X1487 To Mr. ______ Hs{Lord Ernest Hives - Chair}/CTS.{C. Trot Salt - Carburation}18/KW.19.11.34. Bentley Carburation - Needles. On the standard Bentley car in cold weather, the snap acceleration is not as good as it could be. This feature is worse on some cars than others. The worst conditions under which this characteristic can be noticed is travelling along a level road at 30 m.p.h. with just sufficient throttle opening to keep the car moving at this speed. If the accelerator is then snapped down, the response is not as instantaneous as it should be. On a "bad" car, the necessary improvement can be brought about by richening the mixture on the hand control 3 notches. The result is the impression of a much improved getaway. With reference to memo. LA.{L. A. Archer}1/T.25.10.34, the Test Dept. had carried out tests to determine the value of a pair of experimental needles. These needles for recording purposes were known as "Blank" needles. The difference between these and the present standard 'A,W' needles is as follows:- (1) Richened up slightly around 30 m.p.h. full throttle. (2) Weakened slightly at high speeds to counteract higher petrol consumption. In the memo. LA.{L. A. Archer}1/T.25.10.34, it is shown that these "blank" needles were too weak at top speeds but nothing is mentioned about snap acceleration at 30 m.p.h. We are handing over to the Test Dept. however a pair of needles marked "Z". These have the same characteristics at middle speeds as the "Blanks" but the necessary mixture strength restored at high speeds. We will be very interested in the comments of the Test Dept. on these needles, as it is desired to know to what extent the production car can be improved by a slight alteration in mixture strength at the right spot. Hs{Lord Ernest Hives - Chair}/C.T.Salt. | ||