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).
Engine carburetter settings and performance characteristics.
| Identifier | ExFiles\Box 66a\1\ scan0040 | |
| Date | 29th January 1925 | |
| R.R. 493A (50m) (D.B. 175 25-9-24) J.H.D. -3- EXPERIMENTAL REPORT. Expl. No. REF: Hs{Lord Ernest Hives - Chair}/ACL/LG29.1.25 Petrol consumption and power curves for both dynamo-meter and Test Bench will be supplied in due course. On the above setting the engine should open up with the mixture control in central position without any 'popping back' - the engine, of course, being at normal temperature and the spark in its normal advanced position. It should however 'pop back' on opening up with the mixture control full weak. At all speeds the exhaust from the engine should be perfectly clear and free from black smoke. On sudden acceler-ation however, it is correct for there to be a momentary 'black puff' from the exhaust which indicates that just for the instant the carburetter supplies an over-rich mixture which is necessary for good acceleration. The weakest maintained position of the carburetter when correctly set should not vary more than plus or minus 2 notches from central position. It must be remembered that at speeds below that at which the air valve starts to lift - such as dead-slow running on the road - it is necessary to make use of the mixture control to obtain a rich enough mixture to give even running. When the final adjustment has been made the jets nuts should be marked in the usual way which is the practice with the 40/50 H.P. Carburetter. Hs{Lord Ernest Hives - Chair}/ACL. | ||