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).
Letter to Zenith Carburetter Co. regarding needle movement and fuel flow issues on Phantom III carburetters.
| Identifier | ExFiles\Box 122\2\ scan0045 | |
| Date | 24th June 1936 | |
| X1.0.33 Exptl. Dept. Hs{Lord Ernest Hives - Chair}/Swdl.{Len H. Swindell}9/JH. 24th June, 1936. Messrs. Zenith Carburetter Co.Ltd., Honeypot Lane, Stanmore, Middlesex. Dear Sirs, We hear that you are experiencing trouble with regard to obtaining sufficient needle movement on the Phantom III carburetters. We have found that by machining down the float stop to the extent of .150 the needle movement is increased from .075 to .120. In this condition the float did not foul anywhere before coming on to the stop. In your letter of June 2nd, you say that by reducing the needle movement from .100 to .080 with a head of 27" the flow was reduced only from 120 pts/hr. to 117 pts/hr. We have taken a flow test for variation of needle movement under a 27" petrol head as delivered by the S.U. petrol pump used on the Phantom III chassis and find that the maximum flow is not reached until approximately .120 needle movement. The curve also shows that at .100 movement the flow is 178 pts/hr. and at .080 is 156 pts/hr. As we are on the border line of starvation we would recommend a .120 needle movement which we have proved can be obtained. | ||