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).
Adjustments to magneto and battery ignition timing specifications for the 20 HP and EAC.2 engines.
| Identifier | ExFiles\Box 37\1\ scan 271 | |
| Date | 27th August 1924 | |
| Contd. -6- EFC9/T27.8.24. this is liable to be exceeded by a few degrees, so that the maximum advance of the battery ignition may be this amount less than the 60° b.d.p. stated. A photostat diagram (assuming 10° a.d.p. full retard) of the 20 HP. battery and magneto ignition(upon an ignition lever travel base)is also attached to E's copy. Reverting to the requirements of EAC.2 and in particular to the magneto requirements as specified, copy of which specification was sent to E.{Mr Elliott - Chief Engineer} under cover of our EFC4/T30.5.24, and the third par. of which specification is the basis of the present tracing labelled "General Magneto Specification" referred to earlier in this communication, will E.{Mr Elliott - Chief Engineer} kindly note that we have altered one figure in this par., namely 450 r.p.m. to 600 r.p.m., so that the sentence now reads:- "The automatic advance should commence at a magneto speed not greater than 600 r.p.m." (We have accordingly shown our general magneto specification advance curve as beginning to advance at 400 engine r.p.m.) The exact setting of the magneto and battery ignitions on the EAC.2 engine at full retard perhaps can scarcely be considered to be fixed, but on the assumption that the R.R. battery ignition is set 10° a.d.p. at full retard,and that the magneto (to the required specification) is 3° b.d.p. at full retard, a diagram representing the EAC.2 conditions has been drawn on an ignition lever travel base, and a photostat copy of this also is attached. | ||