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).
Engine and drivetrain issues including knocking, detonation, carburation, and clutch performance.
| Identifier | ExFiles\Box 72\2\ scan0053 | |
| Date | 15th October 1925 | |
| Oy6-E-101525 -3- October 15, 1925. starting knocks and wear of cylinders and pistons. At present the knocking continues for several minutes after starting. (Engine oil used Socony "Medium", our standard oil for test chassis). There is no indication that extra oil is required when running full throttle except a slight rattle or roughness at the higher speeds, especially on the overrun. Our experience with imported Silver Ghosts makes us think that this may be due to the slipper being too tight for our oil. (We have to reduce the friction to 170 lbs. ins. to get smooth running.) The engine is smoother since disconnecting the butterfly valve in the exhaust. Detonation. As received, the engine "chirped" whenever the clutch was let in on any gear except first. It also chirped at low speeds on any hill. Disconnecting exhaust butterfly has reduced this tendency a lot. Running after switching off. If the engine is at all warm it continues running after switching off. It is therefore necessary to stop it by closing the throttle, and then it will not start on the switch. There must be some hot spots in the cylinder which cause this. Changing from Lodge to Champion spark plugs has not altered the tendency. Carburation. This must be exceedingly good to give so little dilution. The engine does not load up. There is a weak spot in acceleration just as there is with the present car, that is when the throttle is opened there is a distinct lag before the engine really begins to pull. Lincoln, Packard, etc. give a fierce tug when the throttle is first opened and get away from us for the moment. Do you think our air valve opens too quickly? (not quick enough, probably) Valve Springs. We have broken a valve spring. We found it after 2500 miles, but it may have been broken before, as it did not affect the running at moderate speeds. Clutch. This is not as soft in engagement as the cone clutch. Unless one is very careful in letting it in, it shudders and jerks the car. | ||