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).
The difficulties of setting the Phantom III ignition timing and proposing a potential solution.
| Identifier | ExFiles\Box 91\1\ scan0157 | |
| Date | 25th November 1935 | |
| To Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} +30D Hs{Lord Ernest Hives - Chair}/FD.{Frank Dodd - Bodies}19/KW.25.11.35. Phantom III Ignition Timing. We are having extreme difficulty in setting the ignition timing quickly and accurately on the Phantom III. It takes a mechanic over an hour to time an engine and then it is not guaranteed to be within 2° on the flywheel markings. The main cause of the trouble is in locating the cam on the taper spindle to the correct setting. The cam having 12 alternative positions makes it a very fine adjustment, added to which there is the backlash from the timing gears to allow for when tightening down the cam. We feel sure that unless a more simple method for setting the ignition is used on the Phantom III, the timing will never be synchronised and set to R.R. requirements when the car is in the hands of the general public. What we want to do is to be able to rotate the distributor head round the cam to determine the final position, having in the first place fixed the cam as near as possible correctly. We had thought that one of the best ways out of the difficulty would be to have the cam on splines, instead of the taper as at present, with an additional adjustment from the distributor head. Since then, however, we have tried out a mock-up scheme using the present arrangement of cam fixing and an additional adjustment by rotating the distributor head, as per attached sketch, with success. If this scheme were used it would be necessary to increase the present range of movement on the tower, for the advance and retard, to allow for the distributor head adjustment. The control on B ignition tower would also require moving from inside the V to the opposite side for accessibility of setting. On doing this we should require an extra control lever to reverse the retard action. | ||