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).
Experimental modifications to the 25/30 ignition governor to improve slow running and reduce detonation.
| Identifier | ExFiles\Box 101\3\ scan0060 | |
| Date | 13th May 1937 | |
| 20 To RHC.{R. H. Coverley - Production Engineer} from Rm{William Robotham - Chief Engineer}/Swdl.{Len H. Swindell} Mx.{John H Maddocks - Chief Proving Officer} c. to Hs.{Lord Ernest Hives - Chair} c. to E.{Mr Elliott - Chief Engineer} c. to By.{R.W. Bailey - Chief Engineer} Rm{William Robotham - Chief Engineer}/Swdl.{Len H. Swindell}5/AP.13.5.37 25/30. SLOW RUNNING AND AFFECT OF IGNITION GOVERNOR. Owing to the complaints received on poor idling and the noticeable improvement obtained by running with the ignition setting at T.D.C. instead of the standard 13° before T.D.C., a governor has been produced experimentally in the endeavour to obtain this characteristic. This consisted of a perfectly std. 25/30 governor frame (T.60879) taken from Production and the shaft made perfectly free in its bearing. The governor spring was as standard T.52103 but in lighter gauge (18.SWG, .048) wire and the initial tension on the weights made a minimum; that is just definitely returning the weights to the stationary position. As tested out on GAS.20 which has a standard unit (turbulent head) the above special governor when set full advance on the hand control at T.D.C. gave identical acceleration performance at speeds from 5 m.p.h. up to 20,30,40,50,60 and 70 as obtained with a standard governor set at 13° before T.D.C. The idling was a definite improvement especially noticeable in smoothing out the 'lurch or thump' that is felt in the car. Additionally, the intensity of detonations was considerably reduced and this will be an appreciable advantage to cars that are running on Shell, as on several cars observed at Cricklewood the detonations were audible in the car. Regarding the deturbulated head which is now standardised and on Production the setting of this same special governor should be 5° before T.D.C. We urgently require your confirmation of our results say taken on six cars with the new standard deturbulated head set at 5° before T.D.C. and six cars with the turbulent head set at T.D.C. continued | ||