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 a No. 3 exhaust valve losing clearance, detailing burnt valve seating bronze and a collapsing tulip edge.
| Identifier | ExFiles\Box 11\3\ 03-page166 | |
| Date | 6th July 1930 | |
| To: Hs.{Lord Ernest Hives - Chair} From G.W.H. Hôtel de France, Châteauroux, Indre. 6/7/30. We have dismantled the cylinder head to ascertain the reason of No. 3 exhaust valve losing .012" clearance in approx. 1000 miles. There is no sign of the valve having become burnt. There is a considerable quantity of the valve seating bronze burnt on to the valve. The diameter of the valve head has decreased .25 m/m.{Mr Moon / Mr Moore} The valve stem, measured from the underside of head to top of stem has increased in length approx. .0312". It would appear that the outer edge of the tulip is collapsing. We cannot detect any other feature in the cylinder head or in the tappet mechanism to account for the loss of valve clearance. The valve does not show any sign of being any more overheated than the rest of the valves in the cylinder head. They are as stated S/SLV valves E.78493. It may be possible that the cause is due to local heating round these valves, the coring of the cylinder head not being correct, especially that we take the exhaust from this valve to the hot spot of the carburetter. We suspect this as also being the cause of our overheating of the water. We have fitted two new valves, one in No. 3 exhaust and one in No. 4 exhaust, to ascertain whether it is a feature in the valves themselves or otherwise. We have taken the opportunity to fit the American valve springs at the same time, putting the closed/coil at the bottom, this being logical, as we have not had a reply from you re our query. We shall be running again this afternoon. The weather here continues to be very hot, 33°C. being registered yesterday in the garage. G.W.Hancock | ||