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).
Continued analysis of the advantages and disadvantages of a carburettor type, this being page 2.
| Identifier | ExFiles\Box 121\2\ scan0079 | |
| Date | 23th January 1929 guessed | |
| contd :- -2- (1) They give good power output due to the low depression at which they operate. The low speed full throttle power is usually good because here the depression is at a minimum. (2) Due to the unrestricted or straight through shape they have a good pressure restoration effect giving the maximum suction at the choke for the minimum induction pipe depression. The straight through form avoids fuel deposition and greatly assists in eliminating 'loading up'. (3) The diffuser type jets used with these carbs. give good atomisation and greatly assists uniform distribution. (4) Simplicity. The disadvantages are :- (1) Poor snap acceleration from idling speeds which becomes more difficult if the chokes are provided for high power. This also becomes more manifest on a heavy car, where good power is wanted due to the necessarily slower acceleration of the car giving a greater divergence between the increase of engine speed and the speed at which the throttle is opened. (2) Poor low speed and idling operation due to the lower part of the speed range being controlled by the throttle position relative to the low speed discharge unit. Carb. therefore not automatic for varying speed and throttle position over this range. (3) Mixture usually has to be set over rich at the lower speed range in order to obtain reasonable acceler- ation. contd :- | ||