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).
Modifying the Autovac petrol feed tap on Phantom & 'SS' models to prevent petrol starvation by enlarging the tap holes.
| Identifier | ExFiles\Box 64\1\ scan0029 | |
| Date | 1st February 1929 | |
| To DA.{Bernard Day - Chassis Design} from Hs{Lord Ernest Hives - Chair}/AJL. c. to BY.{R.W. Bailey - Chief Engineer} E.{Mr Elliott - Chief Engineer} c. to MOr. X7510 Hs{Lord Ernest Hives - Chair}/AJL/LG4. 2. 29. AUTOVAC PETROL FEED (PHANTOM & 'SS{S. Smith}'). X7510 X3579 Several cases of petrol shortage have been traced to foreign matter in the cork faced tap used on the autovac. A very little foreign matter indeed in this tap is sufficient to cause starving. We find that the tap is barely large enough to pass the quantity of petrol required by the engine. The holes in the tap are at present .218" dia. and to supply the maximum engine demand under all conditions they must be increased to .250" dia. The following figures indicate the loss of flow in the tap as compared with a barrel type having the same bore, and also the increase of flow due to enlarging the holes. The maximum flow ever required by the engine is 100 pts/hr. (this figure allows a good safety margin.) Type of tap. Petrol head. Petrol flow through tap - pts/hr. -------------------------------------------------------------------------------------- Cork faced tap .218" holes. Full autovac. 90 Barrel tap .218" holes. " " 113.8 Cork faced tap .218" holes. 1" head of petrol. 58 Cork faced tap .250" holes. 1" head of petrol. 106 The present overall size of the tap is barely sufficient to take the increase in size of the holes without increasing the difficulty of making the tap petrol-tight - it will be necessary therefore to modify the tap to accommodate this alteration. contd :- | ||