THE new premises of Messrs. J. A. Prestwich and Co., Northumberland Park, Tottenham, N., are admirably suited for the turning out of motor cycle engines, which the company commenced to manufacture in 1903, previously having been established for a long time as mathematical instrument makers. One of the latest improvements brought out by Mr. Prestwich is a valve cotter extractor, consisting of a flat piece of forked steel, suitably bent to the required shape. The two ends of the fork fit on to the radiating fins when the valve is raised. The valve cap is then removed and the tappet lowered ; the valve is pressed down by a screwdriver and the spring being compressed, the cotter may be easily withdrawn. This is a simple and effective tool, which should prove of great benefit to riders of machines fitted with J.A.P. engines.
The New Junior Twin.
Quite a new engine which has been brought out by the company is a 3 h.p. twin, dimensions 60 x 76 mm. The engine is practically a small replica of the 8 h.p., and is fitted with side by side valves. The lubrication in this, as in all other J, A. P. engines, is interesting. A relief valve is fitted on though inner side of the timing gear case, permitting though oil adequately to lubricate the timing gear wheels. At the bottom of the timing gear case is a small drain hole to allow the surplus oil to run back into the crank case. Mr. Prestwich has all but completed the Tourist Trophy engines.
These will be a single-cylinder lightweight, dimensions 76 x 65.5 mm., a lightweight twin, 60 x 60 mm., valves placed side by side, while the following engines have been constructed for the Senior Tourist Trophy Race:
A twin-cylinder, 76 x 64 mm., with overhead valves, and a single-cylinder, 85 x 85 mm., with side by side valves.
These Tourist Trophy engines will be fitted with a ball bearing crankshaft and ball bearing big ends, the latter being of substantial construction. It is interesting to note that throughout the whole of last year Mr. Prestwich spent much money and much valuable time in experimenting to find a really durable exhaust valve, and we are happy to be able to state that his efforts have been rewarded with success.
The Motor Cycle, 1911 Page 333.
If you have further information or a query related to this page, please contact us
