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).
Modifications to reduce carburetter suction noise.
| Identifier | WestWitteringFiles\J\February1923\ Scan35 | |
| Date | 6th February 1923 | |
| To R.{Sir Henry Royce} from Hs.{Lord Ernest Hives - Chair} c.c. to CJ. c.c. to E.{Mr Elliott - Chief Engineer} c.c. to Ds. c.c. to BY.{R.W. Bailey - Chief Engineer} ORIGINAL. Hs{Lord Ernest Hives - Chair}4/LG6.2.23. CARBURETTER NOISE. X 4228 We have proved that if we do away with the annulus left between the spigot on the carburetter and the recessed portion of the induction passage formed on the cylinder, and also if we turn off one of the collars between the low speed jet, we get a consistent amount of suction noise from all carburetters with no signs of a whistle. This noise can be decreased appreciably by adding a light aluminium pressing over the air inlet. We have confirmed by tests on the bench that we lose no power with this. We have also confirmed that removing the collar on the low speed jet is not detrimental. When the 20 HP. carburetter is modified as above, it is definitely quieter than the present 40/50. The extra advantage gained by silencing the air passing through the air valve ports is not very great, unless it is done very thoroughly and the air inlet taken a long way back on the car. We propose sending out a standardisation sheet for these modifications so that we can get them on the cars as soon as possible. In connection with these tests we found that the suction noise on the 40/50 car when fitted with the exhaust heated throttle is more than with the water heated throttle. This is due to the fact that the hot air pipe to the low speed throat has been considerably shortened. We find that by making a suitable contd:- | ||