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).
Investigation report into engine misfiring on a 20/25 HP chassis, caused by temperature-related variations in the contact breaker gap.
| Identifier | ExFiles\Box 57\2\ Scan028 | |
| Date | 6th June 1930 | |
| X.5783. WE.27. 6.6.30. X.5680. X.5783. INVESTIGATION OF MISFIRING ON BATTERY IGNITION ON 20/25 HP. CUSTOMERS' CHASSIS A case of misfiring on the "pick up" on a customer's chassis in the Repair Dept. was brought to our notice by EP.{G. Eric Platford - Chief Quality Engineer} and we accordingly went out on the road to investigate the cause. After confirming that the H.T. circuit of the ignition i.e. distributor wires, and plugs were OK. by changing over to magneto ignition, the contact breaker was examined. The tungsten contact points were in very good condition but the gap at break was only .005" (the engine was well warmed up). Upon readjusting the gap to .020" and trying the "pick up" again the misfire had disappeared and could not be reproduced. After allowing the chassis to stand and cool down the gap contracted to .014". It would appear therefore, that a certain amount of distortion occurs on the contact screw support due to expansion and contraction and if the contact gap happened to be initially small when cold misfiring due to closing up of the gap might occur. This is only a theory and we suggest we experiment further to prove this. H.E.West. | ||