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).
Ignition advance characteristics and speed curves for Bentley 60 and Bentley 80 models.
| Identifier | ExFiles\Box 168\3\ img183 | |
| Date | 23th May 1939 | |
| 6119. S. Es/RC.{R. Childs} BY/RD.2/B.23.5.39. IGNITION ADVANCE CHARACTERISTICS. Herewith, advance stroke speed curves for Bentley 60 and Bentley 80. On attached sheets C.1 and C.2, we show in full line the Bentley 60 and Bentley 80 ignition curves as requested by you. Superimposed on these we show in dotted lines, curves produced by governors which Messrs. Lucas can guarantee in quantity production. It will be noted that the nominal curve (crossed dotted line) is fairly close to our requirements (crossed full line) for Bentley 60, except that they cannot produce the wavy effect asked for. In the case of Bentley 80, the nominal curve would again be fairly close if the speed commencement was increased a little, but since we wish to make one governor do both jobs, we should be pleased to know whether the Bentley 80 curve with this limit is acceptable, as shown on C.3. We agree that the speed range limit which Messrs. Lucas asked us to accept, is wider than we have hitherto accepted, but if we insist on reducing this limit, then the price of the unit is going to rise owing to the special hand work required on production. On C.2. we have shown the speed range and the possible difference in speed of every degree of advance on all distributors. To be consistent we would suggest that in future, the minimum and maximum speed of distributor shaft be stated per degree advance of distributor rotor, as in the past requests have varied. Examples as follows :- 2° + 2° (flywheel) = 500 r.p.m. 5° to 6° (flywheel) = 500 r.p.m. 3° (distributor) = 270 - 370. (distributor). but we feel that if we have one method of stating our requirements the issue will be considerably clarified. -Contd- | ||