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).
Magneto ignition requirements and related engine firing issues on 40/50 HP cars.
| Identifier | ExFiles\Box 4\5\ 05-page198 | |
| Date | 12th May 1921 | |
| Memo from Sr. C. to HE. C. to RPU. X430 X677 EP{G. Eric Platford - Chief Quality Engineer}20/P12.5.21. X 1812 MAGNETO IGNITION REQUIREMENTS. We are glad to note your comments in R12/G10.5.21 on HE's report, which we are very pleased to see he was taking up, as it is certainly a matter which requires going into thoroughly. We certainly can endorse the fact that it is the behaviour of the magneto on the car which is of vital importance, and which at present is far from satisfactory. We feel, therefore, at this stage that we might bring forward a few points in connection with our experience and knowledge gained in this respect with the current 40/50 HP cars. 1. The irregular firing for slow speeds throttled down is chiefly due to the position of the plug. Whether magneto or battery is used, we find that the intermediate position is always worse in this respect. This point has been realised by several customers, and in some cases they have changed over the wiring or fixed all the plugs in the pocket position. They have done this contrary to our recommendations. Also, they have not appreciated that in doing so, the "timing" of the ignition is altered. 2. The plug in the pocket position is practically unaffected by oil in the combustion chamber, and the lubrication of the cylinders may be fairly liberal without causing the plug to give trouble due to over-oiling. This, however, is not the case with the intermediate position of plug, and the quantity of lubrication one can allow for the cylinder is practically controlled by what this plug will stand. Our action is always to encourage ample lubrication of cylinders and pistons. 3. Plug failures and ignition troubles certainly are very seriously affected by faulty carburation and uneven lubrication, and although the plugs may not definitely cut out, irregular firing can invariably be cured by cleaning the plugs. 4. The oxidising of the electrodes chiefly takes place with the plugs in the pocket position. The presence of oil in the intermediate position appears to prevent this trouble. We also find that the | ||