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).
Test report on a Watford EC6d Magneto, serial number 82558, with a modified air gap.
| Identifier | ExFiles\Box 48\2\ Scan298 | |
| Date | 8th July 1925 | |
| To Wd. {Mr Wood / Mr Whitehead} from EFC. {E. Fowler Clarke - Electrical Engineer} c. EY. V8796 EEC10/T8.7.25. X4181d. WATFORD EC6d MAGNETO No. 82558 with INCREASED AIR GAP BETWEEN THE POLE SHOES AND THE SLEEVE. We have now completed a tests on this magneto, comprising firstly Inspection and Production Test, and secondly, tests to General Specification of Magneto Performance. The magneto passes the production test with one unimportant exception, that as might be anticipated, the low speed sparking speed in the fully retarded position was 10 revs. higher than the limit given, e.g. 200 as against 190. On this magneto the following points were observed :- Air gap between pole shoes and sleeves .006". Clearance between sleeve ring and bearing .002". Tangential force to move cam lever 2.25 lbs., the limits which are being worked to at the present moment being 2 to 4 lbs.; so that it may be that this increase of air gap is a considerable help in regard to the operation of the magneto by the oil relay system. Timing range 63°. As regards the performance of the magneto on athe standard specification, a diagram is given showing a comparison of observed performance on the leaky annular spark gap with that required in par.(5) of the General Specification, and it is thought that Messrs. North may be interested in this diagram. It is seen to comply with it with one minor unimportant exception. Contd. | ||