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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 timing comparisons and a summary of observed mechanical failures.

Identifier  ExFiles\Box 133\1\  scan0009
Date  13th March 1936 guessed
  
-4-

A similar process as for the P.V.G. is now carried out, save that in this case, Bentley timing is used on the Rudge and there is no exhaust pipe ramming to speak of. The result of this is that, using this timing, the standard Bentley and the Rudge are about on a par, whilst the "high Power" head shows a decided advantage and approaches very near the aero performance.

These curves are very illuminating for, while it is appreciated that they are pure estimates for the most part, they would seem to indicate that the Rudge does not give such an outstanding performance asmight at first sight seem the case. From the point of view of detonation, however, there does seem to be a gain over the car unit, and this is probably due to the symmetrical disposition of valves and plug, and the absence of pockets, protruberances or sharp corners in the head.

Mechanical Failures.

The following mechanical failures have been experienced during the period covered by this report. Hardy coupling discs have caused most trouble, eleven having failed. Four cylinder studs have fractured due to vibration, and three exhaust valves have failed, having fatigued at the tool marks. Wear is rather rapid in the inlet guides, and exhaust valves have shown a tendency to pick up due to running dry. Cam followers have worn rather thin and been replaced, and splines on the L.H. axle and coupling spider have failed, presumably by fatigue. Also one slight case of piston seizure has been experienced due to excessive detonation and resultant overheating.
  
  


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