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 test results, including power loss, supercharged tests, and various mechanical failures.
| Identifier | ExFiles\Box 133\2\ scan0063 | |
| Date | 26th July 1934 | |
| -5- A further reduction of 13° in exh. lift duration, resulted in a power loss: this curve had to be terminated at 3750 r.p.m. owing to failure of the tappet, thus preventing further investigation. More tests are to be carried out when an improved design of tappet (which will stand the high accelerations of short duration valve lift) is fitted to the engine. It is expected that a slight gain will be obtained when the best timing is found. Supercharged Tests. A series of tests has been carried out on the "Ramp" head under boosted conditions (up to 3 lbs/sq.in.). The results are given on Sheet 9, and call for no further comment. MECHANICAL FAILURES. Cylinder Head Gaskets. It has been found necessary to fit a solid aluminium gasket between the cylinder head and barrel, as we have experienced two failures of C/A.{Mr Adams} gaskets; one after forty minutes running only. Both these failures occurred with the Ramp head and it was found that the gaskets were burnt at a point diametrically opposite the sparking plug. Valve Springs. We have experienced one broken valve spring (exhaust) after 34 hrs. 50 mins. running on the standard head and with normal timing (except for short periods). Exhaust Valve. After 37 hrs. 50 mins. running, the "Silchrome" exhaust valve (which had been fitted in error) in the standard cylinder head was found to be cracked. Since fitting a valve in KE.965, no more cracking has been experienced; but on three occasions trouble has been caused by the valve seating becoming so hammered that, after cooling down, the valve failed to make a gas-tight joint. These three failures occurred after 46 hrs. 10 mins; 5 hrs. 15 mins, and 6 hrs. 30 mins, running. This trouble has not been experienced on the Ramp head. | ||