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).
Summary of findings and proposed modifications for silent tappet and oiling system issues.
Identifier | ExFiles\Box 182\M18\ img040 | |
Date | 16th April 1934 | |
G.W. Hancock, Esq., Hotel de France, Chateauroux, Indre, France. I have now had a chance of going over the silent tappet job and seeing where we were getting to and the following is a brief summary of the present position :- (1) We find that the only set of tappets which is at all consistent is that running on J-III. These have a Zenith filter put temporarily in the system. Until this filter was fitted they were very inconsistent. The Design people knew about this but owing to some political issue did not incorporate it. Therefore we consider it is useless to run silent tappets without some sort of filter and would ask you to rig one up temporarily. (2) We proved that a hardened rocker shaft was necessary to prevent sticking of the eccentrics on J-III. Somehow a soft shaft was instructed for the Phantom. We shall have some hardened shafts running here during the next day or so. Cadillacs somehow get away with a soft shaft, copper plated. (3) Owing to the way we feed the oil into the plungers, as soon as the car stands the lubricant can run away from the top of the cylinders so that these become dry and on re-starting the tappet is noisy. To overcome the trouble we are drilling the feed oil hole so that it comes out at the top of the cylinder. At the present moment the plunger itself meters the oil; therefore when the oil hole is drilled above the plunger we are going to make it so small that it will be the metering restriction (see E.84423 enclosed). We find that Cadillacs, in order to ensure that each tappet gets the correct amount of oil in spite of their location at different points in the feed system, drill a different size metering hole for each tappet; i.e., those closest to the supply have the smallest hole. This strikes us as being a sound idea, and we are adopting the same method. You might modify your tappets on these lines, working to E.84423 attached. | ||