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).
Issues with mixture controls, cold weather performance of trials cars, and the introduction of new sparking plugs.
| Identifier | ExFiles\Box 131\4\ scan0042 | |
| Date | 4th February 1937 | |
| Rm{William Robotham - Chief Engineer}/CWH from Rm.{William Robotham - Chief Engineer} Franco Brittanic Auto Co.Ltd., 12 Avenue George V, PARIS 8. Rm.{William Robotham - Chief Engineer}15/M.4.2.37. Thank you for your notes. Dealing with these as follows:- I. We cannot believe that the Mixture Controls on the Bentley are any worse than the starting carburettor which we used to have on the PHI and II. Personally nothing annoyed me more than the spring operated starting control on the 25/30, as it is almost always necessary to shunt the car after starting up, and to manipulate the control with one hand and the steering wheel with the other is very difficult. Your suggestion of limiting the number of notches on the quadrant which can be used, however, does seem to be more reasonable, the only drawback being that I have found the whole range is required if one is to get away satisfactorily on a cold morning. However, we will make some tests as soon as we get some cold weather. Personally, I believe, that the very thin oil we propose to use will prevent cylinder bore wear due to using over rich mixtures. I am also positive that better oil filtration will improve matters. This will be on production shortly. Ph.III Trials Cars. The trials cars people can use Castrol XL any time they like provided they do not let the car stand outside in wet weather. So can the customers. Our experience has proved that when the car is kept in a heated garage there is no trouble. If, however, the car is going to be left out and the temperature falls appreciably below freezing, then as you know, the tappets are likely to stick. We have increased the plunger clearances on production which will improve matters. We find that bad consumptions are generally speaking due to defective grummets. Even with your felt pads in the rockers the leak of oil down the valve stems can be very bad. We are hoping to arrange a system so that the valve is not dependent on the grummets to seal the stem. Sparking Plugs. We are going to fit the new K.L.G. Sparking Plugs on all trials cars. | ||