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).
Dual carburettor modifications to improve idling performance.
| Identifier | ExFiles\Box 123\1\ scan0050 | |
| Date | 24th April 1940 | |
| - 5 - The dual carburettor with 36 m/m throttles is normally fitted with 36 # (.106" dia.) secondary air bleeds. Considerable improvement in idling was obtained by reducing these bleeds to 60 # (.040" dia), and compensating for this reduction in air by increasing the bleed numbered (1) on the sketch from .033" dia. to .055" dia. This is consistent with past experience that the best idle system is one in which air is bled to the petrol as early as possible. It may, therefore, be said that the secondary air bleed should be reduced to a limit beyond which it will not perform the function for which it was placed there. The improvement value of this modification is almost as great as that due to changing from 1 1/8" to 1 1/4" bore induction pipe. RM{William Robotham - Chief Engineer}/TAS.{T. Allan Swinden} RM{William Robotham - Chief Engineer}'s note. Should like actual consumption figures comparing 30 m/m and 36 m/m throttle bodies at an average speed of 40 M.P.H. on a give and take road. | ||