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).
Experiments with doming on platinum and tungsten screw points to improve initial contact bedding.
| Identifier | ExFiles\Box 35\6\ scan 290 | |
| Date | 5th July 1927 | |
| EFC2/T5.7.27 -3- Contd. In all the other four samples given this time, no trimming was required. A criticism of these points which may be given is that the initial bedding is not sufficiently correct. The present standard platinum points are produced both flat, and we know that fair results are obtainable when starting with flat points with absolutely correct bedding, but we do not consider we can depend upon such correctness of bedding upon production, and with that in view, some of /our experiments are being done with a slight amount of doming on the screw point only (both platinum and tungsten) in order to ensure an initial contact not on the edge. It will be seen that in the good case where the current was reversed 4 times per minute, it has been an advantage to have the screw point so domed, and that the area of contact has gradually spread as the platinum has been consumed. This is the condition for which we hope. As to whether the slightly domed platinum screw points will ultimately be standardised remains to be seen from experiments. This morning we have inspected s/x ignitions on cars on test in order to see with what kind of bedding of the platinum points these are started off, and we find the result to be as follows :- Contd. | ||