Fig. 2. Cylinder Block With Head Removed
The location of the water vents is also shown, through which water is circulated to prevent the cylinders from overheating which would cause the pistons to “stick” from expansion.
[Fig. 3]. The top or head of the motor is removed, exposing the combustion chambers. These chambers must be absolutely air-tight as the charge of gas drawn in through the inlet valve is compressed here before the explosion takes place, and low compression means a weak explosion, which causes the motor to run with an uneven-jumpy motion, and with an apparent great loss of power. A copper fiber insert gasket is placed between the top of the block and the head before it is bolted down. This gasket prevents any of the compression from escaping through unevenness of the contact surfaces, as metal surfaces are prone to warp when exposed to intense heat. It is necessary to turn the bolts in the head down occasionally, as the heat causes expansion. The following contraction, which loosens them, results in a loss of compression and a faulty operation of the motor.
Combustion Chamber
Spark Plug Vent
Water Circulating Vent
Bolt Holes
Fig. 3. Removable Cylinder Head (Reversed)
The spark-plug vents through the head are usually located directly over the piston although in some cases they are over the valve head and in some motors which are cast without a removable head they may be at one side of the combustion chamber. The location of the spark-plug does not materially affect the force of the explosion, although when it is located directly over the piston a longer plug may be used, as the pistons do not come up flush with the top of the block, and a spark-plug extended well into the combustion chamber will not become corroded with carbon or burnt oil as is usually the case with a plug which does not extend beyond the upper wall surface of the combustion chamber.
[Fig. 4]. The plunger or piston is turned down to fit snugly within the cylinder and is cast hollow, with two shoulders extending from the inside wall.
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