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 development including governors, ignition systems, camshaft modifications, and performance issues.
| Identifier | ExFiles\Box 101\3\ scan0059 | |
| Date | 6th May 1937 | |
| -2- In the meantime we are endeavouring to produce a governor characteristic that will enable a later static timing and also investigating any improvements by minor alterations in the carburettor and induction pipes. We should like Rm{William Robotham - Chief Engineer}/Wst. to make the ignition system to cope for plug gaps up to .035 without misfires on "pick-up". (b) Future 30 H.P. cars where no additional expense is incurred by new features. Confirmation of improvement in idling obtained with the Ex.24268 camshaft as reported when originally tried in Sg{Arthur F. Sidgreaves - MD}'s. car and on Wraith II No.2 Unit with a view to standardisation. We want to see by experiment if this is the best that can be done with existing cam forms. On this shaft the standard inlet cam (218° duration) has been substituted for the standard exhaust cam (233° duration). The result is that the positive overlap of 3° at .020 clearance is reduced to 12° negative overlap. Regarding the power output, the modified camshaft is down in power by 5-6 B.H.P. at high speeds and gives almost identical power at low speeds. Of the complaints received on the 25/30 whilst at Cricklewood poor slow running was the most outstanding. Though spitting in the silencer is a common complaint, none of the cars in which I was concerned could be called bad and the spitting only amounted to the noise of a small stone hitting the silencer on the over-run. Another trouble which I noticed on most 30 H.P. cars and yet about which there is little complaint is what appears to be noisy bottom tappet rollers. Rm{William Robotham - Chief Engineer}/Swdl.{Len H. Swindell} | ||