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 issues for car 7-EX, specifically firing in the exhaust, self-ignition, and running backwards after extended mileage.
| Identifier | ExFiles\Box 1\3\ B001_X 93-page53 | |
| Date | 4th June 1926 | |
| To Hs.{Lord Ernest Hives - Chair} from R.{Sir Henry Royce} c. to BJ. Wor.{Arthur Wormald - General Works Manager} c. to RG.{Mr Rowledge} CWB. c. to BY.{R.W. Bailey - Chief Engineer} FN. X93 R6/M4.6.26. 7-EX - FIRING IN EXHAUST ETC. X.8040 X.8230 X.699 XG12 X.93 7-EX has run 8,600 miles mostly in France I think without any attention as regards filters, decarbonisation, etc. Even with poor petrol it does not seem to detonate very much, and could I think be quite well altered from 4 to 1 compression ratio to 4.3 to 1 by fitting the latest experimental pistons of any one of the three types should they prove successful. This engine for some reason only very rarely fires in the exhaust, even with the cutout open. It has occurred to me however that this phenomenon might be less when the engine is carboned up somewhat, which I think may be its condition, because this particular engine shews the phenomenon after a hard run of self ignition when the ignition is turned off. This has resulted in the engine running backwards. It was not overheated and the water temperature was about our usual 70 oC. It was this that made me think that after the 8,600 miles it might have a fair amount of carbon within the combustion chamber. This may be causing the self-ignition, and it may also be the reason why the firing in the exhaust with a closed throttle is less than usual. On a few occasions it has been run rather short of water; through forgetting the shutter control and allowing it to boil away. | ||