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).
Technical memo regarding the development and difficulties of the R.R. Semi Expanding Carburetter.
| Identifier | ExFiles\Box 179b\2\ img064 | |
| Date | 8th November 1932 | |
| To H.{Arthur M. Hanbury - Head Complaints} From Hs.{Lord Ernest Hives - Chair} c. to Sg.{Arthur F. Sidgreaves - MD} Wor.{Arthur Wormald - General Works Manager} c. to H.{Arthur M. Hanbury - Head Complaints} Dn. c. to Hy.{Tom Haldenby - Plant Engineer} Hdy.{William Hardy} Hs.{Lord Ernest Hives - Chair}7/WJ.8.11.32 X70801 R.R. SEMI EXPANDING CARBURETTER. These carburetters are now in production on the Phantom and we expect to be delivering cars with them in about a months time. The carburetter promises to be very good but one must anticipate that the development of it will continue for some time. Our present views on some of the difficulties which have arisen are as follows :- STARTING. - The most efficient form of starting is the present starter carburetter used on the old type carburetter. There is no question about the efficiency of this arrangement because it has satisfied all the customers in U.S.A. on cars being used under the most extreme conditions and compared with all the fancy gadgets which the Americans have used for starting. The advantage that the starter carburetter has is that the main throttle is closed and that the whole of the suction is available for the starter carburetter. With the throttle edge scheme of starting there is a considerable leak round the throttle which reduces the suction on the starter carburetter. A cold engine takes a fair amount of power to keep it turning. The throttle setting for slow running is not sufficient to do this and we have to open up the main throttle to keep the engine turning. Another point we are debited with on the latest Phantom 11 is the fact that we have recently increased our compression ratios from 4.75 to 5 1/4 /1. This increase in compression ratio means that the starter motor has more work to do and the engine is not turned over so fast. We have still some work to do on the latest carburetter before the starting is equal to what we have been used to. We notice that the latest Solex carburetter is using a starter carburetter similar in principle to what we have used. | ||