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).
Testing procedure for an ignition distributor's contact breaker and spring tension.
| Identifier | ExFiles\Box 70\4\ scan0122 | |
| Date | 9th February 1928 guessed | |
| -2- Contd. Also see that the cam itself is greased. The tangential force at lever pin radius necessary to advance or retard the ignition distributor shall lie between the limits 1½ to 2½ lbs. weight. (1) The contact breaker shall be connected up to an ammeter, a twelve volt battery, and a non-inductive resistance of zero temperature coefficient, all in series, the last named being of such a value as to permit the passage of exactly one ampere when the points are in contact. The distributor shall then be driven at a speed of about 700 r.p.m. The correct contact point setting will then be such as to permit the passage of a current of .55 ampere during rotation. The resulting contact gap should be noted for future reference and should lie between .017" and .021" but the adjustment should initially be carried out as above. During this test it should be noted that there is no indication of fouling between the rotor blade and the H.T. spark points in the distributor head. (2) The distributor should now be speeded up to 1800 r.p.m. when the average current should not be less than .48 ampere. If it is, it is probable that the contact breaker lever spring is faulty and another spring should be tried. (3) By means of a spring balance suitably attached to the contact end of the rocker arm, the tension required just to break contact (and indicated by the ammeter in circuit) should be noted. Contd. | ||