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).
Test results and conclusions from altering camshafts to observe effects on power figures and valve bounce.
| Identifier | ExFiles\Box 124\2\ scan0007 | |
| Date | 5th January 1940 | |
| - 2 - The exhaust system used for silenced tests was B.80 twin manifolds EB.4291/2 to a standard Bentley II single silencer. Champion N.6 Sparking Plugs were used for slow running tests. These were now and used only for this purpose. Champion NA.{Mr Nadin}10 being used for power figures. Valve bounce and slow running figures were obtained with engine silenced. Slow running figure being obtained with engine running "light" i.e. Heenan & Froude brake disconnected, also with Ignition initial setting timed to spark at T.D.C. Results. In putting the power figures on paper, we have taken as a basis for comparison the original B.80 Camshaft, EB.4105, (long duration inlet and exhaust). Graph No. S.113. gives the power value for the Camshaft Ex.33975, (angle between cams altered to give reduced overlap). Graph S.114. gives the power value for the camshaft Ex.33975 (angle between cams altered to give reduced overlap). Tabulated Sheet No. S.115. gives "results at a glance", which include power figures; tappet noise characteristic; slow running value, and valve bounce speed. It should be noted that valve bounce figures refer to the inlets, as the exhausts do not bounce within the normal engine speed range. This is due to the reduction of loadings by virtue of their being side valves and working almost directly off the shaft. The conclusions to be drawn from these results, are briefly that, in considering the alteration which produced the final camshaft tested (Ex.33975), namely, altering the angle between the cams of camshaft EB.4312, we would gain more by altering the angle between the cams of shaft EB.4105, in the same manner. We would say however, that this conclusion has only been arrived at by testing all three shafts in the same engine. Fm/F.J.Hallam. | ||