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 operational challenges and considerations of using tungsten points in distributors.
| Identifier | WestWitteringFiles\Q\2April1927-June1927\ 86 | |
| Date | 1st May 1927 guessed | |
| -3- Contd. unfortunate that it was considered necessary for the tungsten points to be touched. Concerning the good operation of tungsten points generally, we have noted the following points :- (1) Cleanliness is necessary. RR. distributors on chassis get oily and dirty due, we think, to (a) Close proximity of the ball bearing. N.B. On the U.S.A.Bosch there is no ball bearing in this position. In the Delco-Remy protection from the bearing oil is afforded by the provision of a felt washer. (b) Oxide formed by the jump spark distributor dusts about. N.B. Delco-Remy use wipe distributor and U.S.A. Bosch umbrella rotor. Umbrella rotor for RR. distributor is one of the experiments at present in preparation. (2) Correct initial bedding is essential - a very small amount of doming of the screw point only is necessary to provide for this. We have some time back arranged for this amount to be .002" (centre of point above periphery) on the tungsten points. Subsequent uneven or bad trimming is bad for performance. (3) Sparking at contacts must be kept down to a minimum on account of resulting oxidation. Experiments of maximum possible condenser in present condenser case are in preparation. Lack of cleanliness increases sparking, with given condenser. It will thus be seen that in some ways the use of tungsten is more difficult than that of platinum, which latter has the advantage of not so readily oxidising. In view of the fact that we have got a satisfactory 10,000 mile test of tungsten points on your 7-EX, are you of the opinion that we should now circulate a standardisation sheet ? EFC. | ||