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 comparative testing of different ignition system contact breaker points.
| Identifier | WestWitteringFiles\Q\2-July1927-September1927\ 99 | |
| Date | 9th September 1927 guessed | |
| -2- Contd. The result of this test would appear to show the necessity of some flexibility for the screw point. On the Remy contact breaker itself the surface of the screw point stands .450" above the face of the metal projection into which the point is screwed. This multiplies the sideways effect of any flexibility in the supporting plate. Std. Up-to-date tests of standard tungsten points under Standard conditions as a control experiment. A sample of this is sent to you labelled Std. As in the other two cases, no misfiring occurred but the condition of the points is, we think, the least good of the three. It is certainly a good deal inferior to the case with the scrubbing action. No. 20. The fourth sample sent to you labelled 20 is a U.S.A. Bosch point, run with our own electrical system. This point was domed as received from U.S.A. and initial contact was made on the centre. This has not done at all well. It was removed at 5600 miles because the tungsten point gap had become too small for the points to break, owing to the wear of the rubbing block. We have now the following against U.S.A. Bosch as compared with Delco-Remy, being the results of comparative tests under similar conditions :- (1) Contact points do not run anything like as well. (2) A contact point came loose on one of the levers. (3) Rubbing block wears more rapidly. (4) Coil failure occurred. So far as this evidence goes, therefore, it would appear to show that our own equipment with tungsten points is better than the U.S.A. Bosch. We will carefully watch the result of the present (second) test of scrubber without damper now in progress, and if this is consistently good at, say, 3000 miles we will inform you. We understand that it is desired to re-design this arrangement to make it suitable for the cars, the main reason being that the L.T. terminal would be on the wrong side. EFC. | ||