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).
Carburetion systems for the Spectre and 20/25 HP models.
| Identifier | ExFiles\Box 93\2\ scan0048 | |
| Date | 8th July 1935 | |
| To R.{Sir Henry Royce} c. to SG.{Arthur F. Sidgreaves - MD} c. to HGR. c. to Hy.{Tom Haldenby - Plant Engineer} c. to Lox. x308 Rm{William Robotham - Chief Engineer}/Ma.14/KM.8.7.35. Carburetion - SpectreCodename for Phantom III & 20/25 HP. On Rolls-Royce cars for the last 25 years we have always had the carburetter below the induction pipe. On the SpectreCodename for Phantom III, the induction system being in the Vee, this is not possible. On the large bore 20/25, where the carburetter has to be on the same side of the engine as the exhaust pipe, it is almost impossible if good distribution is to be obtained. We have therefore been forced to develop another system. The biggest difficulty has been the slow running. The attached report from Hs{Lord Ernest Hives - Chair}/CTS.{C. Trot Salt - Carburation} indicates the line of development pursued. The best system developed so far is a downdraught carburetter with a four port induction pipe. We think this is quite as good as our systems of the past for slow running. The two carburetters we have been working with are Stromberg and Zenith, both of the downdraught fixed choke type. Having only just stabilised the induction system, we are not yet in a position to pass a comprehensive opinion on the carburetters, but shall shortly be able to do so. So far we have only run this four port system on the 20/25, we are fitting it to Wor{Arthur Wormald - General Works Manager}'s car during the next few days. The existing SpectreCodename for Phantom III cylinder head being different from that of the 20/25, it is problematical whether the system which is successful on the 20/25 will necessarily work on the 12 cylinder. We rather think it will, however, and are rigging up a car for test before asking for any designs. | ||