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).
Technical update on testing and development of carburation, tappets, pistons, crankshafts, and brakes.
| Identifier | ExFiles\Box 91\4\ scan0008 | |
| Date | 21th May 1935 | |
| -2- Slow Running & Carburation. We have promising 4-port and 6-port systems running on the 20/25, and we are trying to finalise both systems so that we can demonstrate them and decide which is the better. The work done should enable us to demonstrate a large bore unit on the 20/25 with a view to improving the performance of this car. The Cambridge Exhaust Gas Analyser has been obtained and is proving itself very useful. We have demonstrated that with the shortest duration camshaft that we have we can get reasonably good slow running with the existing four carburetters, without much loss of horse power. Tappet Wear. We have tested the chromium plated tappets which have been produced for us by the Rover Company. These have shown less tendency to pick up than the previous case-hardened tappets, but cannot yet be considered satisfactory. The roller tappets are now being fitted for test. Piston Knocks & Vernilling. The longer skirt pistons with the longer liners are better for piston knocks than anything we have previously tried, but are not completely free from trouble. We have received SpectreCodename for Phantom III pistons ground to the Aerolite con rods and these will shortly be going on test. Crankshaft Period. The larger crankshaft damper has now been tested. It has undoubtedly reduced the crankshaft period to a very marked extent but has not entirely eliminated it. We think that we require a slightly heavier flywheel to complete the cure, and are producing one experimentally. for Brakes. The Phantom type brake adjustment parts are now nearing completion and will be fitted shortly. We have carried out some maximum braking tests and shall be issuing a report shortly. The hydraulic tappets with the reduced eccentric ratio have been detailed, and should reduce the tendency for the valves to be held open when cold. | ||