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 testing and fault diagnosis of Watford Aero Magnetos type IS.12, numbers 83134/5.
| Identifier | ExFiles\Box 43\4\ Scan018 | |
| Date | 24th November 1926 | |
| EFC. WB.{Mr Brazier/Mr Bell}114. 24.11.26. WATFORD AERO MAGNETOS TYPE IS.12 Nos. 83134/5. These magnetos were returned to us for a short test, the testers reporting loss of power due to ignition. We found that running in the advanced position wi the magnetos, particularly No.83134, only gave two sparks per rev. suggesting in the first instance that the internal timing was too far advanced, and secondly that there was a certain amount of asymmetry in the magnetic flux paths. In the retarded position the sparking was O.K. even at speeds in the neighbourhood of 4500 r.p.m. thus shewing that the magnets were not weak. On one of the magnetos (No.83135) we found that the distributor moulding had punctured at a place where the insulation was very thin. This we considere serious and steps should be taken to increase the insulation thickness at that point. (The punctured part of the distributor was where the moulding had been cut away to accommodate the contact breaker cover). These magnetos are being fitted to the engine again with the lever fixed at retard and the engine timing advanced correspondingly and the faulty distributor has been temporarily repaired by inserting sheets of mica between the moulding and the earthed metal case. EFC/H.E.West. | ||