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).
Carburetter performance, focusing on issues with slow running, mixture control, noise, and building up.
| Identifier | ExFiles\Box 178\4\ img040 | |
| Date | 25th April 1932 | |
| -2- to be forced downwards from the holes in the diffuser tube. We did not have a chance to investigate this at the time. It is, however, receiving attention. It was found necessary in order to get a quick start up to have the throttle shut down to its dead slow idling position which is not easy to find with the hand governor control. For this reason we think a definite throttle stop should be employed as it has been our experience that all throttle edge slow running carburetters behave similarly. Now that we employ throttle edge slow running we do not find the same need for a throttle governor as due to the richer mixture at very small throttle openings we do not get banging on the silencer. Slow Running. On the test bed and idling on the car the slow running is more positive and can be got slower than the Std. chassis carb. On the road on 19-31. the slow running on top gear below 6 M.P.H. was not good and we rather suspected the carburetter. We have, however, refitted the Std. carburetter as a check but could not improve the slow running. We think this dismisses the fault as due to the new carburetter. Mixture Control. The mixture control appears very ineffective at anything above low powers - i.e. when the small end of the needle taper is in the jet. We think the mixture control could be reduced to two operating positions only - the starting position and the normal warmed up position. Noise. The carburetter is rather noisy on the road and roaring on accelerating is evident. The intake at present employed is made up on the 'Air Maze' principle. The inside of the outer air intake cover is fitted with three layers of 16 S.W.G. copper gauze. Considerable improvement in the air intake silencer we think can yet be made and this is receiving attention. Building up. This carburetter appear to be quite free from building up troubles since the draining scheme has been fitted round the outside of the small choke. Hs{Lord Ernest Hives - Chair}/A.C.Lovesey. | ||