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).
The performance and adjustment of carburettor mixture control.
| Identifier | WestWitteringFiles\M\2Jan1925-March1925\ Scan23 | |
| Date | 1st January 1925 | |
| R.R. 493a (50m) (D.B. 175 25-9-24) J.H.D. EXPERIMENTAL REPORT. -2- Expl. No. REF: Hs{Lord Ernest Hives - Chair}/ACL/LG15.1.25. The notches on the mixture control were plotted against the r.p.m. Therefore the number of notches rich on the mixture control indicate actually the number of notches which the mixture is weak when the control is in its mean position. Expressing the quality of the mixture by the number of notches on the control was taken as a very convenient means of showing graphically the metering of the carburetter under various conditions. The mixture control had seven notches adjustment on each side of the mean position. In taking the readings for the curves which we have supplied it was found that sufficient adjustment could not be obtained on the control, so it was moved a certain number of notches in relation to both jets so that the necessary mixture could be obtained and the total number of notches noted. The curves on SHEET 2. show that from the point at which the air valve starts to lift, the mixture richens slightly until the diaphragm uncovers the ports on the high speed throat and starts to dilute the charge by air through this throat. From this point the dilution is too great, or we may say that the depression does not increase enough, and the mixture weakens rapidly until there is sufficient depression in the high speed throat to cause the high speed jet to deliver fuel. From here the mixture starts to return to its correct strength which it attains by the time the extra air ports start to admit air. Onwards up to its maximum speed, the mixture is fairly proportional. contd :- | ||