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).
Letter to Delco-Remy & Hyatt Ltd. discussing spark gap issues and ignition timing for a Bentley.
| Identifier | ExFiles\Box 82\4\ scan0337 | |
| Date | 12th June 1936 | |
| X 200 Exptl. Dept. Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer}14/KW. 12th June, 1936. W.O. Kennington, Esq., Messrs. Delco-Remy & Hyatt Ltd., 111, Grosvenor Road, LONDON, S.W.1. Dear Kennington, We are not finding that a wide spark gap clears up all our distribution troubles, as suggested by Mr. Taub, but we are struggling along with it and I think that ultimately we shall find that a .030" gap is practicable and with this we shall get better idling. Attached is a resume of some tests we have already done, which you might compare with the figures obtained on your Vauxhall. With regard to the Delco Remy ignition timing, we are at present developing a new type of cylinder head, and we find that to get good, smooth idling we require an ignition set at 0° top dead centre, but by the time we reach 1,000 r.p.m. we want 13° flywheel advance to give optimum pick-up. In other words, the ignition governor has got to be sufficiently sensitive to start advancing at about 125 revs., and should move rapidly from thence onwards. The attached graph SP.{Mr Spinney}29, curve 4, indicates the ideal ignition curve. Now we very definitely cannot do this with our governor, and if you can say that you can do it, and do it consistently on production, I believe it would be an unanswerable argument in favour of fitting the Delco Remy distributor to the Bentley. I should be glad to hear from you about this in the immediate future. Yours sincerely, | ||