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).
Power curve tests for a Standard Bentley Head with modified valve timing and no overlap.
| Identifier | ExFiles\Box 133\2\ scan0100 | |
| Date | 17th November 1934 | |
| To - Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} from Hs{Lord Ernest Hives - Chair}/Wd.{Mr Wood/Mr Whitehead} [strikethrough]c. to Wer.[/strikethrough] [strikethrough]c. to E.{Mr Elliott - Chief Engineer}[/strikethrough] Hs{Lord Ernest Hives - Chair}/Wd.{Mr Wood/Mr Whitehead}1/GB.17.11.34. [Handwritten Signature] Rm{William Robotham - Chief Engineer} STANDARD BENTLEY HEAD POWER WITH NO OVERLAP. In anticipation of the reduction in valve opening duration consequent on fitting Cadillac tappets, a set of power curves was taken on a Standard Bentley Head with standard valve timing and an alternative timing with, in both cases, the durations modified to reduce the overlap from 11° to 6° and to 0°. The results are shown graphically on the attached blueprint, from which it will be seen that the standard timing is less sensitive to change of overlap than the alternative timing and that [strikethrough]there[/strikethrough] it results in a reduction of only approximately 2 lbs/sq. inch in B.M.E.P. over the whole speed range. [Handwritten Signature] Ll Smith [Signature] Wd.{Mr Wood/Mr Whitehead} [Handwritten Note] When we get final results of Close centre valve head & final figures for valve lift - req'd attach blueprint. (Sheet 1) we shall put in hand another camshaft with less overlap. [Typed] Hs{Lord Ernest Hives - Chair}/Wd.{Mr Wood/Mr Whitehead} | ||