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).
Investigations into the effect of the vacuum feed on slow engine running.
| Identifier | ExFiles\Box 40\4\ Scan122 | |
| Date | 14th August 1925 | |
| R.R. 4034 (10 M) (D.D. 51. 12-6-25) J.H.D. EXPERIMENTAL REPORT. Expl. No. REF: Hs{Lord Ernest Hives - Chair}/AJL/LG14.8.25. RE. VACUUM FEED. We have carried out considerable investigations on the effect of the vacuum feed on slow running. It can definitely be stated that the richening up effect takes place just after the float chamber has been emptied. The air valve is shut and the suction valve open, a highly carburetted mixture is sucked into the induction pipe and sufficiently richens up the carburetter mixture to upset the even running of the engine. We have analysed a sample of the gas taken in from the Autovac and find it very rich in petroleum vapours. We have not been able to detect any difference in the richening up due to the temperature of carburetter, engine, Autovac etc. The effect is just as marked when everything is cold as when the engine is running at normal temperature, and everything else heated up accordingly. We have tried introducing the Autovac gas into the induction pipe at various points with a view to distributing it better, so that the effect might be made less noticeable, but without success - the effect of fading away is the same wherever the Autovac gas is introduced. It is not possible to condense the vapour on its way from the Autovac to the induction, the time element is apparently too small to allow of this. Neither increasing nor decreasing the air space above contd :- | ||