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).
From Mr. Caswell to Mr. Olley concerning testing of the Derby Hot Throttle system on car 102-CE.
| Identifier | ExFiles\Box 50\3\ Scan266 | |
| Date | 22th May 1923 | |
| COPY. To Mr. Olley. May 22nd.1923. From: Mr. Caswell. re. Derby Hot Throttle, etc. We have run this 10,000 miles on 102-CE, most of the time during the winter. It has been used with and without drains and boilers, and as far as the operation of the engine is concerned it is not possible to distinguish between the two systems. In the winter, we found it impossible to make a cold start without flooding the cylinders with gas, which also poured down the exhaust valve stems unless we used boilers. We found the small Derby boilers to be too small to prevent flooding cylinders. During the warmer weather with the Derby Pilot Jet cut down to 1 1/2 turns, we get wet cylinders and valve stems by starting after car has stood all night in the shop, temperature of 66°. This occurs if pilot jet is turned off after four seconds only. This has been tried several times. Yesterday morning, May 21st.1923, air temperature 60°, a start was made by turning pilot jet off instantly and running on carburetter only. There was, therefore, no chance of flooding cylinders with gas from the pilot jet. After 1 1/4 minutes running, and by that time throttle was too hot to place the hand on the under side, gas was pouring down numbers 3 and 4 exhaust valve stems in such quantitiy that no trace of oil was left on tappets. The bore of the unions on end of induction pipe is .250 and the inside diameter of pipe leading from boilers to the ends is .240. (5/16 copper pipe). The downtakes to the boilers are 1/2" steel pipe the copper pipes having been found to crack after a year or so of use. There is no mystery about the pipes or unions or anything in connection with the job. The reason Derby cannot reproduce our troubles is due to the absence of the one essential part - American gasoline. E.W.C. | ||