One of the most successful American air-cooled motors is that constructed by the firm of Nordyke & Marmon, of Indianapolis, Ind. For several years past the Marmon 4-cylinder V, or 90-degree motor, has been one of the standard American makes. This year the company produced a larger motor having eight cylinders in rows of four set at an angle of 90 degrees, but for 1908 this huge model has been dropped, and only the 4-cylinder, air-cooled V motor and an ordinary 4-cylinder vertical motor with water-cooled cylin- ders will be built. A decided improvement in the new air-cooled motor is a detachable head, which is shown in the illustration. This head is fitted to the cylinder with a ground joint, and is held in place by four rods which bolt it to the crank case. Besides the usual radiating flanges, the head contains the inlet and exhaust valves and ports, so that there are no extra valve cages to be released before the valves can be removed. Access to the valves is greatly simplified and easy for the chauffeur, and in case it is necessary to grind these valves, the whole head can be instantly removed and the valves ground without the danger of getting any emery into the cylinder. Furthermore, by this construction' it is made easy for the chauffeur to scrape o u t the cylinders and remove any carbon deposit from the cylinder or the cylinder head. This is something that it is sometimes necessary t 0 do, especially with an air-cooled motor, whefe carbon deposits in the cylinder or the head are apt to cause premature explosions Beyond the bringing out of a 4-cylinder vertical water-cooled motor, the Marmon engines have not been changed any during the past year. They still retain the same system of force-feed lubrication by forcing oil through a hollow crank shaft to all the bearings. This system, as well as the car, was fully described and illustrated in our Automobile issue two years ago, and we refer our readers to that issue for a complete description of the machine as it stands to-day.
This article was originally published with the title "Improvements in the Marmon Air-Cooled Motor" in Scientific American 97, 19, 322 (November 1907)