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).
Letter from Zenith Carburetter Co. Ltd. advising on the correct carburetter and choke size for a 3½ litre engine.
| Identifier | ExFiles\Box 122\1\ scan0117 | |
| Date | 1st June 1931 | |
| 81053. CARS DRIVEN BY OUR STAFF ARE AT CUSTOMERS' OWN RISK AND RESPONSIBILITY. Telegrams: "ZENICARBUR, PHONE," LONDON. Code: A.B.C. 5TH Edition. Telephones MUSEUM 9106-9. THE ZENITH CARBURETTER CO. LTD. 40-42, NEWMAN STREET, LONDON, W. 1. 1st June 1931. Messrs. Rolls-Royce, Ltd., DERBY. [Stamp: RECEIVED 2 JUN 1931] Also at LYONS, PARIS, DETROIT, MICH. (U.S.A.) MILAN, THE HAGUE, TURIN. [Logo: THE SOCIETY OF MOTOR MANUFACTURERS & TRADERS LTD] [Logo: THE MOTOR TRADE ASSOCIATION] Your Reference Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer}5/KT. Dear Sirs, We have duly received your letter of the 29th ultimo and noted your query concerning the size of carburetter suitable for a 3½ litre engine giving its maximum power at 3,500 R.P.M. The chart to which you refer has been established assuming that the engine was fed through a single barrel carburetter and should not be used literally in the case of a twin carburetter like our 36 D.U.P. If your induction pipe is designed so that three cylinders are fed through one throttle bore only, you should find a suitable size of choke by joining by a straight line the 1.8 mark on the scale for cubic capacity with the 3,500 mark on the scale for revolutions per minute. You will then see that the proper size of choke should be between 19 and 20, and taking -contd.- | ||