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).
Clutch 'jagger' issue and special valve guide clearances on a 20 HP car.
| Identifier | ExFiles\Box 5\6\ 06-page038 | |
| Date | 22th October 1928 | |
| To R.{Sir Henry Royce} From Hs.{Lord Ernest Hives - Chair} c. to BJ. Wor{Arthur Wormald - General Works Manager}: c. to E.{Mr Elliott - Chief Engineer} DA.{Bernard Day - Chassis Design} c. to BY.{R.W. Bailey - Chief Engineer} X5300 He4/LG22.10.28. 20 HP. 12G-4. X5300 X5060 The clutch on this car was inclined to jagger before the car was sent to WW. but we thought there was a chance that it might improve. At the first opportunity it will be necessary to dismantle and examine it. In the meantime the action of it will be improved if the clutch is doped with oil and paraffin. There are four .25 holes drilled in the flywheel to act as drain holes - our method is to half fill a syringe with equal parts of paraffin and engine oil, depress the clutch and syringe the mixture through one of the holes, then run the engine for a few minutes with the clutch being depressed occasionally. The clutch may be inclined to slip after a few minutes of this treatment but it will soon pick up the drive. The valve guide clearances on this engine are special. There is only a definite clearance of .001". A little time ago we reduced the guide clearances from .005" exhaust and .004" inlet to .003" exhaust and .002" inlet. We had not intended that 12.G.4 should go away with only .001" clearance, it was done to see what margin we had. The fact that it gave no trouble whilst the car was in Derby, it was overlooked. There is, however, no other car running with this small clearance. The rocker shaft oiling on this car is standard and is identical to all previous 20 HP. engines we have delivered. We are anxious to get more oiling on to the 20 HP. rockers. The difficulty on contd:- | ||