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 and testing of a carburettor and air silencer system.
| Identifier | ExFiles\Box 13\4\ 04-page176 | |
| Date | 6th November 1933 | |
| -2- He/Bwdl.17/KT.6.11.33. Running with the complete air silencer fitted it was found that the depression at the jet base was .4" H2O higher than in the stand pipe, so that other than there being no petrol in the stand pipe air was bleeding into the jet supply. In order to make this system function correctly it is necessary to have the stand pipe depression definitely higher than at the jet base. The limit is the height of the top of the stand pipe above the petrol level in the floatchamber which is 2.5". With this in view it was decided to make a depression difference of 1.00 which has a sufficient safety margin both ways and attained by alteration to the position of the floatchamber vent. This modification is shown on V.1682 and deletes the adaptor L.83985, resulting in a final depression when running at 3000 R.P.M. of 5.2" H2O at the jet base and 6.1" H2O in the stand pipe. Metering of the carburetter is very good and runs on the weakest maintained line throughout the range of speed and loading. Final choice of a suitable needle valve will be made on the result of the road test of the carburetter, the needle for use on the test bed being to V.1651. Another modification, is - V.1680, where the existing flow from the jet was restricted. This carburetter should embody the light float 36 S.W.G. which is now on production with the new petrol level setting of 1.375 below the parting surface, in order to prevent flooding on an incline. The worm and wheel adjustment of the slow running, eccentric feed hole to Scheme 1639 (2) has not yet been tested. Power loss to the air silencer (Led.5494) with alternatives to the gauze cleaner, in the form of Vokes cleaners, have been taken. The latter is a corrugated ring of felt bound by gauze each side, the difference in the two submitted for test being the thickness of the felt, .062 and .075". | ||