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).
The preliminary tests of a new twin-choke carburettor for the Phantom II.
| Identifier | ExFiles\Box 13\3\ 03-page266 | |
| Date | 24th December 1930 | |
| To R.{Sir Henry Royce} From Hs{Lord Ernest Hives - Chair}/ACL. c. to Sr. Wor.{Arthur Wormald - General Works Manager} c. to E.{Mr Elliott - Chief Engineer} Da.{Bernard Day - Chassis Design} c. to Hy.{Tom Haldenby - Plant Engineer} 87080. Hs{Lord Ernest Hives - Chair}/ACL.1/MJ.24.12.30. TWIN CHOKE CARBURETTER FOR PHANTOM II. We have made some preliminary tests with the new twin choke carburetter on Phantom II with very promising results. The first test shows us a power gain of 11% at 1500 R.P.M. and coming to approximately the same power as the standard chassis carburetter at 2500 R.P.M. The hot spot appears very efficient and it is necessary to use only a very small outlet to the atmosphere to prevent it getting too hot. Distribution is very good but we have not yet tried it without heat to the hot spot. Starting up is very easy and there appears no need for a separate starting carburetter. The engine runs very well as soon as it starts from cold whereas with the standard carburetter it is necessary to operate for a time on the starter carburetter. The petrol flow into the float chamber is inadequate and for the moment we have used a 12 ft. petrol feed head to enable us to run to full power. We are going into this question next. The engine can be throttled down to a much slower idling speed than the standard carburetter but we think we may be able to do quite satisfactorily with only one slow running discharge at the throttle edge - the same as on our new carburetters. The carburetter roars very badly at full throttle which is a fault common to most three cylinder induction systems. Hispanos used to be very bad in this respect but they have now got over the trouble by coupling the air intake to the crankcase and sucking all their air through two breathers via the crankcase. This appears particularly efficient and is now standard on these cars. We do not think we can effectively silence the carburetter with any ordinary intake without losing a lot | ||