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).
Procedure from Zenith Carburetter Co. for setting carburettor throttle conditions.
| Identifier | ExFiles\Box 122\4\ scan0156 | |
| Date | 15th June 1938 | |
| THE ZENITH CARBURETTER CO. Limited. Sheet No... 2.. Messrs. Rolls-Royce Ltd. 15/6/38 carburetter throttle, whilst still maintaining the desired pressure drop across the carburetter at full throttle conditions. The arrangement we adopt is first to set the regulating valve to give the required pressure drop across the carburetter, say 2-3" mercury at full throttle, or, alternatively, pass the desired quantity of air per minute through the carburetter at full throttle, and then to close the throttle to a position which will give .3 lbs. of air per minute at a depression of about 18" of mercury. It will be found in general that this depression under these conditions is more than 18" mercury, and it is then we start to bleed out this depression by slowly opening the balance valve until 18" mercury is reached. If the carburetter throttle is then put over to full throttle, it will be found that the air flow through the carburetter has been reduced slightly, and it is then necessary to open the main regulating valve a little further to re-establish the former conditions as regards full throttle air flow. Closing now the carburetter throttle back until .3 lbs of air per minute is obtained, it will be found that the depression at slow running might still be 18", or probably a little bit higher than that figure, when re-adjustment again must be made and the process repeated backwards and forwards until one obtains the desired air flow, or, alternatively, the desired pressure drop across the carburetter at full throttle in conjunction with a flow through the carburetter of .3 lbs. of air per minute at 18" mercury under slow running conditions. These conditions having been established, it is then only necessary to manipulate the carburetter throttle valve at increasing air flows of .5 .75 1 1.5 lbs. of air per minite, and so on, right up to full throttle, without re-adjusting any other part of the apparatus. The mixture curve at full throttle air flow of course is obtained by closing down the main regulating valve only. We think the diagrammatic arrangement drawing explains the plant in general. The pump which we have fitted was obtained from The Norman Engineering Company, Hytor Works, Commerce Way, Purley Way, Croydon, who can also supply the special relief | ||