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).
Comparison of two inlet pipe designs for the B.V. induction system to improve starting mixture distribution.
| Identifier | ExFiles\Box 99\1\ scan0057 | |
| Date | 22th August 1939 | |
| To By.{R.W. Bailey - Chief Engineer} from Rm{William Robotham - Chief Engineer}/CTS.{C. Trot Salt - Carburation} c. Da.{Bernard Day - Chassis Design} c. Da{Bernard Day - Chassis Design}/McS. Rm{William Robotham - Chief Engineer}/CTS.{C. Trot Salt - Carburation}13/MH.{M. Huckerby}22.8.39. B.V. INDUCTION SYSTEM. Purpose of test. To compare:- (a) EB.4995 (ECD.1382) Inlet pipe (cast-in starter passage). (b) EB.4123 (ECD.758) Inlet pipe (Central starter feed released for 50 chassis). The reason for the change in design is to improve starting mixture distribution as explained in our memo Rm{William Robotham - Chief Engineer}/CTS.{C. Trot Salt - Carburation}2/JH.12.5.39. In a previous report (Rm{William Robotham - Chief Engineer}/CTS.{C. Trot Salt - Carburation}8/JH.10.5.38) we have shown that the dimension of the balance between the two halves of the induction pipe, controls part throttle correction of mixture strength (using 2 S.U. carbs. on a six cylinder engine). The size of the starter passage in the pipe EB.4995 (having allowed for skin friction) is the same as the normal balance hole in the centre of the pipe EB.4123). We find, however, that the cast-in starter passage does not give the same correction for part throttle metering as the plain drilled hole. This we say is due to the fact that the pulsations take place along the main bore of the pipe, and while the plain drilled hole lies directly in the path of pulsations, the connections of the cast-in starter passage are on the sides of the pipe, and are therefore not subject to the same effect by pulsation. All that is required, therefore, is to drill a .375 dia. hole in the blank section in the centre of the pipe. This can be done by a long drill, through the core plug in the end of the pipe. In the case of the Corniche pipe the hole should be .4375, and an important point arises here:- | ||