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 into battery ignition failure, concluding that wider spark plug gaps prevent misfiring at low charges.
| Identifier | Morton\M22\ img055 | |
| Date | 30th December 1919 | |
| To BN.{W.O. Bentley / Mr Barrington} from R.{Sir Henry Royce} Copy to CJ. " " HS.{Lord Ernest Hives - Chair} " " CK.{Mr Clark} " " PN.{Mr Northey} " " FP.{F. Potts} " " HM.{Capt. W. Hallam - Head Repairs} X.3129 ORIGINAL. RE BATTERY IGNITION. R1/G30/12/19. 1EX IGN. X.3445 X.1812 X.3763 X.3413 On 1 EX. it was observed that the ignition failed on one of the cylinders when the charges became very light. This caused chunking in the transmission, but only when carefully watched for. In investigating this trouble I determined that it was one cylinder, and removed the ignition plug, which was sent to Derby as defective. In continuing the experiments in the garage, it was found that the same cylinder ceased to fire when the charges became very light indeed, but the missing fire was quite constant and the plugs were moved about until it was ascertained that the missing fire followed the plug. This led to the careful measuring of the gap between the points, when it was found that the plugs with the widest gap continued to fire and those with the narrow gaps started to mis-fire. You will remember that Mr. Platford might be called the high priest of wide gaps for slow running on the battery ignition. This experience strongly supports the practice we adopted, which was advocated by Mr. Platford. I write all this to impress the very manifest necessity of always using the practice of wide gaps for the battery ignition, and also to point out the great advantage of moving the coil to the new position near the distributor, and cancelling the earthed (Contd.) | ||