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).
Instructions and test results for fitting a Chevrolet suction ignition control to a Bentley 3.B.IV unit.
| Identifier | ExFiles\Box 83\1\ scan0390 | |
| Date | 8th March 1937 | |
| 2009 Rm{William Robotham - Chief Engineer}/GWH{George W. Hancock - Head Chateauroux}/IMW.{Ivan M. Waller - Head of Chateauroux} from Rm{William Robotham - Chief Engineer}/CTS.{C. Trot Salt - Carburation} c. to GWH.{George W. Hancock - Head Chateauroux} Rm{William Robotham - Chief Engineer}/CTS{C. Trot Salt - Carburation}4/R.8.3.37. BENTLEY IGNITION. Rm.{William Robotham - Chief Engineer} has instructed us to send you a Chevrolet suction ignition control, to be fitted to 3.B.IV. unit. This device increases the automatic ignition advance at part throttle running, over and above the action of the present mechanical governor. This suction control does not operate at full throttle, so that under these conditions, only the mechanical governor is in operation (as standard). The results of our tests at the Works are as follows. On the test bed, specific petrol consumption is improved by 15%. On the road, at an average of 30 M.P.H. petrol consumption is improved by from one to two M.P.G., and there is a feeling of a snappier engine. These figures agree with the experience of other firms who fit this device as standard. We will be very pleased to have your comments, but under your running conditions (high average speeds) we do not expect much change in petrol consumption. The following are points to be noted in their order, when fitting up this device:- (1) The complete ignition tower is fastened to the crank-case by four nuts. The bracket carrying the suction unit is secured by the two rear nuts. (2) The control plate A.{Mr Adams} is swung round through 180°. (3) The locking screw B. should be removed, and then put in from the opposite side. (4) The control plate A.{Mr Adams} is then connected to the link from the suction unit. (When the unit is thus connected, the hand control is put out of action). The lubricator cap should be removed. (5) The timing is then checked, and, if necessary reset at 4° B.T.D.C. (which is the correct timing for the deturbulated head). When the timing is set, the connecting link to the suction unit will hold the tower in the same position as did the hand control - fully advanced. | ||