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 sparking performance issues and recommended modifications to the Scintilla Co.
Identifier | WestWitteringFiles\V\2January1931-April1931\ Scan060 | |
Date | 3rd March 1931 | |
-3- (8) The low speed sparking was found to be very poor, in fact in the retarded position regular sparking was unobtainable at any speed. The advanced speeds were found to be :- No. 207577 - 300 r.p.m. No. 207580 - 500 r.p.m. These figures being well outside our limits. The poor sparking at retard appeared to be due in some measure, by observation, to sparking over inside the magneto owing possibly to the different position of the H.T. Rotor relative to the projecting metal parts of the case. It does not appear from the above results that these magnetos in their present condition can be recommended as suitable for tests on F.{Mr Friese} engines. At least it would appear that these would be premature until we have persuaded the Scintilla Co. to make the following modifications :- (a) The fitting of stronger contact breaker lever springs and the provision of set up spring buffer behind the lever. (b) An increase of range to 30°. (c) The provision of gauze covered ventilation holes in the armature cover and if possible also in the distributor blocks. (d) The improvement, especially at retard, of the low speed sparking performance on 5.5 mm. three point spark gaps in air (sparking over potential approximately 8,000 volts. We are writing to the Scintilla Co. to put these points before them. EFC. | ||