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).
Performance issues and observations on a vacuum pump, carburetter, water pump, and exhaust manifolds.
| Identifier | ExFiles\Box 11\2\ 02-page064 | |
| Date | 1st January 1929 guessed | |
| -2- VACUUM PUMP TO L.O.P. E 77660 SILENCER FITTED ON RELEASE SIDE OF PUMP. Under normal running conditions the Vacuum pump maintains sufficient vacuum to operate the Autovac and a plentiful supply of petrol is obtained. Its great failing is when the petrol in the rear tank has got down to approx. 1 gallon, or when the main supply is finished and the Autovac tank has been emptied. The speed of the vacuum pump when the engine is turned over by the starter motor is too slow to get a supply of petrol into the Autovac. Under these conditions we have not been able to start the engine, and it has become necessary to fill the carburetter float chamber with petrol to get the necessary speeds for suction purposes. This appears to be the only drawback of the Vacuum pump. INLET PIPE TO L.O.P. E 77653 & CARBURETTER TO L.O.P. E 78397. The carburation is very susceptible to the water temperature, and starting up from cold the engine cannot be opened up for some time until the water temperature has raised to approx. 60°C. It is also very noticeable on the road if the temperature is allowed to drop the engine immediately will show signs of fluttering. With the water and engine hot generally the carburation and distribution is good. Tests taken for building up show very little signs of this trouble. Generally speaking we do not think there is any serious fault. The throttle control spring is a bit too strong to get an even slow running. One notch on the quadrant makes too much difference. Tests on the road showed that this spring gave a speed of 37 to 38 M.P.H. with the throttle lever full open. This is slightly in excess of what is required, 30 M.P.H. being the standard aimed for. The air valve during the first part of the test gave trouble during every run, due to the diaphragm being too large in diameter. This apparently was made too good a fit. We have overcome it by easing it off and polishing. It is now working quite satisfactory. We consider the carburetter is noisier than the present standard Phantom. We presume this is because it is near to the driver. Whether this increased noise will be objected to, we cannot say. The pipe, etc. does not show any failings up to the present mileage. WATER PUMP DRIVE & THROTTLE GOVERNOR TO L.O.P. E 76657. WATER PUMP TO L.O.P. E 77661. The only trouble experienced with this so far has been the unscrewing of the water pump gland nut. This is in a very unaccessible position, two fingers only can be used for tightening the gland nut up, and it does not seem possible to get sufficient load on the nut to make it remain in position. Although the nut has worked loose no water leakage has occured from the gland. The drive appears to be satisfactory. We have not experienced any trouble with the throttle governor. EXHAUST MANIFOLDS TO L.O.P. E 77673. The exhaust manifolds has been a complete failure. The two outer pipes where they converge into one at the bottom have been burnt right through. It would appear that the pipe gets exceedingly hot at this point and it would appear to be advisable that this portion should be made as a casting and should not be lagged. We have fitted a new manifold sent out which has been treated with aluminium by the Schoop method. This has been lagged the same as the first manifold, and further running will verify whether it is a failure or otherwise. | ||