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).
Recurring exhaust valve failure and exhaust system cracking during car testing.
Identifier | ExFiles\Box 5a\2\ 02-page212 | |
Date | 14th November 1928 | |
75840 Hotel de France, Chateauroux. Handwritten notes: E Vetted, BT{Capt. J. S. Burt - Engineer} noted PA{Mr Paterson}, Please return to HS{Lord Ernest Hives - Chair} We ran into serious trouble with the exhaust valves. After we had tried the car early this morning, I decided to stop any further running until we had examined the valves, as there was distinct signs of bad blowing past them. Upon dismantling the head, we found that 2 out of the 6 exhaust valves had started to burn away a spot on the face of the valve. The exhaust valves in No 1 cylinder and in No 6 cylinder we have had to replace, the other three we had and we have been able to face them up. This failure of these has taken place since my run from Paris, and it was probably due to the higher speed maintained on my run down here that started these valves to go, as since then the engine has been running erratic. It was not until last night that we found any tappet clearances had decreased. Examination of the valve seats does not show any signs of burning, and they are in quite a good condition. We cannot detect any hammering having taken place, therefore we cannot definitely find a reason for the cause of the burning, without the clearance has decreased whilst the engine was hot, thus keeping the valves slightly open. The clearances of the tappets, as you will see in my report, were set to .006", and perhaps, up to the moment, been maintained. The valves taken out we cannot definitely say that they have stretched, and we are entirely at a loss at the moment to explain the reason for the decreasing tappet clearance. We see by the Specification that the exhaust valves are made in Firths Crown Steel. The two new valves we have fitted are exactly the same but are a different place number. They are two spares that we brought out for 17 EX IV. Therefore we are not in any immediate hurry for any new valves. Re the exhaust system, we should like to try to bring to your notice the utter failure of the exhaust system. It should be taken up immediately with Lest Wittering. Apart from the failure of the exhaust manifold, the flange on the exhaust downtake pipe is too weak and distorts all over the place, we cannot keep a flat face on the under side of the spherical washer. The lugs are continually cracking, and we are having to have them continually rewelded. This state of affairs has gone on every time we have come out to France to test a 20-H.P car. We are aware that this is a new design, but it is not one atom better than the previous design. The exhaust down pipe itself distorts and pulls and stresses the joint to the exhaust silencer. We are spending half our time trying to keep the exhaust pipes in such a condition that we can run the car. This should not be the case after our reports upon reports of failures. Can we impress that the pipes become almost white hot. This is not because we are driving a car any faster than what an owner would do during a Continental tour. We had this complaint forcibly brought to our notice whilst in Paris. They cannot keep manifolds on customers' cars from breaking, and are having to continually change them. Handwritten note: 14/11/28 | ||