United States Congressional Serial Set

This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1915 edition. Excerpt: ...the piston reaches the end of its stroke. Then replace gear case cover and slip the commutator into place. This method applies equally well to motors having automatic or mechanically operated inlet valves, and usually also to twin cylinder motors, since where there is more than one cam they are usually fixed in their relation to the large gear. In case they are independent of it, they can be adjusted properly by remembering that the exhaust valve must close as soon as the piston has finished its stroke. Similarly, the inlet valve must close at the end of the down stroke immediately following the closing of the exhaust. To time the spark---First: Place the spark lever or grip in such a_ position that the spark will be half way advanced, as in Fig. 1. Second: Beginning at the point where the exhaust valve closes, turn the crank-shaft through one complete revolution, again bringing the piston to the upper end of its stroke and again set it at the highest point in its travel. Third: Set the sparking cam so that the contact spring is just leaving the contact screw, thus causing the spark to pass. Fourth: Tighten the cam in position so that it cannot possibly slip, and replace the binding screw or lock. nut, thus completing the operation. As in the case of the valves, the timing of a twin cylinder motor should give no more trouble than that of a single when it comes to the spark if only the principle of locating the dead center properly is borne in mind. It should be remembered that correct timing is absolutely essential to proper action in the motor and that the process of valve or spark setting is one which cannot be done hastily or carelessly if satisfactory results are to be obtained. In timing either the valves or the spark, it...