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 unsatisfactory bench test performance of Watford IS.12 magnetos, highlighting issues with sparking and timing.
| Identifier | ExFiles\Box 43\4\ Scan066 | |
| Date | 21th February 1927 | |
| XL4021 To Wd.{Mr Wood/Mr Whitehead} from EFC. C A.D. EFC2/T21.2.27 WATFORD IS.12. MAGNETOS NOS.83132/3. The above magnetos were received on the 3rd. inst. On test on the bench we find the sparking of these magnetos in the advanced position to be bad, misfiring occurring at practically all speeds on 5.5 mm. gaps in air. With the lever so retarded sparks become regular up to 3500 r.p.m. to 4000 r.p.m., thus giving the impression that the timing range is too far advanced. This is rather surprising to us in view of the fact that we found the last pair of magnetos, Nos.83119/20 to be better in this respect, and suggested that Messrs. North had probably altered the internal timing, which fact was confirmed by them in their letter It would appear either that they have not altered the internal timing of these two, or can they possibly have made a mistake and altered it in the wrong direction ? The low speed sparking is also poor in relation to the other magnetos which we have tested. We feel sure that these machines would behave rather unsatisfactorily on an engine in the advanced position, especially in the condition when the primary gap increases. Can Messrs. North give any explanation as to why the performance of these machines is so much down on the performance of the previous two which would appear to be quite satisfactory in this and other respects? The difference is so definite that we cannot understand why it can have escaped their own observation. EFC. | ||