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).
Troubleshooting guide table listing engine performance issues and their probable causes.
| Identifier | WestWitteringFiles\N\2October1925-December1925\ Scan196 | |
| Date | 27th November 1925 guessed | |
| -11- TROUBLE: Richness at low speeds light loads. PROBABLE CAUSE: (1) Jet set before air valve starts to lift. (2) Diaphragm set too low down in high speed choke. (3) Spring pressing tightly on air valve when in down position. (4) Leakage passed dash-pot cover. (5) Leak holes too small. TROUBLE: Richness at position where air ports open. PROBABLE CAUSE: (1) Spring pressing too tightly on air valve. (2) Low speed jet too rich. (3) Leakage past dash-pot cover. TROUBLE: Weak at high speeds. PROBABLE CAUSE: (1) Obstruction in jet or filter. (2) Collar on needle valve moved from its correct position which prevents needle lifting to its full extent and thereby restricts petrol flow. TROUBLE: Poor acceleration with no popping back. PROBABLE CAUSE: (1) Air valve not lifting quickly enough due to insufficient leak holes. TROUBLE: Popping back on acceleration. PROBABLE CAUSE: (1) Cold hot-spot. (2) Obstruction in jet or filter. (3) Very rapid lift of air valve due to wear. TROUBLE: High speed jet weak at high speeds and unable to make sufficiently rich. PROBABLE CAUSE: (1) Spring not lifting jet needle or operating toggle not permitting jet to lift to full extent. (2) Filter stopped. | ||