Type "Y" Fuel this nozzle, a cross-section of which appears in Fig. 321, an attempt has been made to partially atomize the fuel before it passes the check valve A. The valve stem B has a series of spiral grooves in its surface. The stem fits the nozzle cavity rather snugly, and the oil is forced to flow along the spiral grooves. This causes the oil particles to separate, and, after passing the valve, the nozzle tip opening completes the breaking-up of the oil into minute globules. The valve is closed by the reaction of the spring. This spring should be compressed about inch when being assembled. This will give the proper tension to the spring. While this nozzle does break up the oil fairly well, the operator must keep the spiral grooves clean. With heavy oil, a deposit of coke will settle on the grooves, choking up the action of the nozzle. In regrinding the valve seat, emery flour, or pumice flour, and vaseline make an ideal grinding compound. The nozzle should be held in one hand, while the fingers of the other hand are used in rotating the valve. The tension of the spring should be partially relieved by pressing inward with the finger. It is not necessary to grind the entire valve face into contact. A light line contact is just as serviceable and much easier to obtain. With this nozzle, as with all others, a spare one should be on hand so that the used nozzle can be removed and soaked in lye or kerosene to thoroughly clean all the parts.
If there is any suspicion that the valve is leaking, the cap of the combustion chamber should be removed. The engineer can then have his helper operate the fuel pump by hand. The oil should jet out of the nozzle tip.in a fine stream that breaks up before it reaches the combustion chamber walls. If the stream of oil is not fine, the nozzle-tip opening is too large and should be replaced with o-ne having a smaller, opening. If the valve leaks, the stream of oil does not cut off quickly. The nozzle tip has two openings. The main opening C is along the axis of the nozzle, while a smaller passage D is at an angle: In operation, when a heavy oil is used, the temperature of the combustion chamber is not sufficient to ignite the fuel. An alloy tube is inserted in the chamber wall; this tube retains the heat much better than the cast-iron combustion chamber. As the oil enters the tip, part of the charge flows out through the angular passage and strikes the hot tube. This assists in the ignition of the main oil charge which has flowed through the axial passage. If the fuel be of light gravity, all of it will flow through the axial passage C due to its low resistance and to the high resistance of the angular pas sage. With light oils little, if any, strikes the hot tube. The nozzle tip has a groove on one side which fits a dowel pin in the combustion chamber. It is imperative that this dowel rests in
this groove to enable the oil jet to strike the hot tube. The nozzle itself is turned on its outer surface and fits very snugly into the engine casting. It is a good plan to clean out the cavity, into which it is secured, to remove any carbon that might pre vent a good bearing.
Oil Engine Fuel nozzle, Fig. 322, employs two spring-loaded check valves. The lower one A, which is immediately behind the atomizer tip B, performs the office of cutting off the oil flow and breaking up the oil stream; this "breaking-up" is assisted by the spring washers which are perforated with a series of small open ings. The upper check C merely assists the lower check valve in sealing the oil line against any danger of back-firing from the cylinder. With any type of nozzle where the check leaks, there is danger of explosions in the fuel line caused by the gas flame in the engine cylinder traveling up through the nozzle. The use of two check valves serves to confine any combustion to the nozzle.
To regrind the valves the nozzle is disassembled at the joint D.
The nozzle tip is also removed. Taking up the lower half, the valve spring guard E should be removed. This frees the spring and allows the valve to drop down. The valve face can then be lightly coated with the grind ing compound. In grinding the valve, a small screw-driver can be inserted in the slot in the end of the valve. No pressure should be exerted against the valve, or the seat will score.
In regrinding the upper check, the spring guard must be un screwed from the nozzle body and the spring removed. A pair of tweezers can be used to grasp the valve stem for the purpose of rotating the valve.
The nozzle end fits against a ground shoulder that effectually prevents any hot gas from sur rounding the nozzle body. As a consequence of this sealing, there should be no coking in the nozzle.
Primm Oil Engine FuelNozzle. —This nozzle, Fig. 323, is built along .standard and accepted principles as regards tip and check valve. The method of connecting the fuel line .to the nozzle is somewhat different from the general practice. The Primm makes use of a yoke connection which admits the fuel into the nozzle at one side, the junction being a ball and socket joint.
In removing the nozzle, which is screwed into the cylinder head casting, if care is not used there is a liability of twisting the nozzle—especially so if a long-handle wrench is used. The best method of removal is to run kerosene around the nozzle to cut away the rust. Then the nozzle should be given a few sharp blows with a copper mallet. This will effectually "break" the joint and allow the nozzle to be unscrewed with a small wrench.