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 hesitation issues and the testing of a float chamber balance scheme.
| Identifier | ExFiles\Box 102\1\ scan0247 | |
| Date | 29th January 1935 | |
| To E.{Mr Elliott - Chief Engineer} c. to Wor.{Arthur Wormald - General Works Manager} c. to By.{R.W. Bailey - Chief Engineer} c. to Mx.{John H Maddocks - Chief Proving Officer} HS{Lord Ernest Hives - Chair}/CTS.{C. Trot Salt - Carburation}27/KW.29.1.35. 20/25 Carburetter (LOP. E.60092). Float Chamber Balance LEC.4292. The above scheme has now been fully tested on the present standard carburetter. Since we issued our report Hs{Lord Ernest Hives - Chair}/CTS.{C. Trot Salt - Carburation}24/KW. 8.10.34, further investigation of this trouble has been carried out, with the following results. Firstly, it is found that the "hesitation" now complained of on production carburetters can be divided into two distinct faults. Although the symptoms of these two faults are almost identical on the road, the individual cause of each fault is quite independent of the other. The worst trouble is the fault as mentioned in the previous report, due to reversal of flow, caused by interference acting on the float chamber depression. This is noticeable on the road, when the throttle is suddenly snapped open, the engine responds immediately, but only by picking up the available mixture in the pipe. After about 6 explosions, the engine appears to miss the next 6 explosions; then straight away pulls full power. The scheme LEC.4292 cures this fault. The second hesitation, not so easily noticed and like the other fault, not prevalent on every carburetter. This is a hesitation most noticeable at 40 m.p.h. Travelling at this speed, if the throttle is snapped open from the fully closed position, the fault is non-existent, but after running long enough at full throttle for the air valve to reach its equivalent lift at this speed, if the throttle is then half closed and straight away snapped open again, the result is as follows :- A fall in power can be felt when the throttle is half closed, and when the throttle is opened again, instead of immediately pulling full power, the power comes back gradually, causing the engine to feel particularly flat. | ||