Model 800: 1956 Imperials and earlier
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from the grommet in the cover unless one or other requires replacement.
Loosen clamp which attaches the burner assembly to heat exchanger and break the seal formed by the gasket. The burner assembly can then be removed with rubber vent tube attached.
c. Inspection and Disassembly of Burner
The nozzle and mixer assembly should receive special inspection before disassembly since the condition of these parts will give an indication of the cause of unsatisfactory operation. The nozzle and inside of mixer can, around the nozzle, will normally be covered with a medium layer of black carbon and the nozzle should have a small gray opening at the orifice. The outer end of mixer will usually be burned to a gray or reddish color and some scaling or loose particles are usually present. These will do no harm.
Indications of improper operation are an uneven build-up of black carbon, or an excessively burned or eroded spot on the mixer. The openings around nozzle must not be clogged with carbon since this will prevent entry of proper amount of combustion air. If these symptoms are present, the condition will not be remedied by cleaning, since it is caused by a one-sided spray from nozzle or by dripping or leakage around the nozzle seat.
The spark plug electrodes will operate properly with a considerable accumulation of carbon and lead but must not be shorted out. If the electrodes are burned, this indicates an improperly directed spray and nozzle or nozzle seat is at fault.
d. Disassembly of Burner
Remove the fuel fitting and screen from fuel inlet. Remove spark plug retaining cap and lift out spark plug. Remove mixer and louver plate assembly by removing three screws in louver plate. Remove nozzle with a 5/8 inch box wrench or socket and remove rubber spacer which is underneath nozzle. Remove solenoid cover, coil, cork gasket; remove three screws in bottom of cup and remove cup, sealing disc, and gasket from burner casting. Invert the casting, and valve spring and plunger will drop out. Remove valve seat retainer from nozzle side of casting, using an Alien wrench (1/4 in. across flats) and remove valve seat and valve seat gasket.
e. Inspection of Burner
Inspect the valve seat for scoring around the sealing surface and inspect the end of plunger. The, plunger contains a rubber insert which must be flat and slightly recessed into the metal retainer. If the insert is uneven, replace the plunger assembly. Do not attempt to clean or repair the nozzle. Replace this unit at each overhaul. Clean burner casting, mixer assembly and spark plug, being very careful not to permit any foreign matter to enter the passages of the burner casting. Discard any defective parts and replace with new.
f. Assembly of Burner
If fuel line inlet screen was removed from burner casting, install a new screen. Install the fuel inlet fitting and tighten. Install the valve seat gasket, the valve seat and the valve seat retainer in the order named, making sure the pointed side of the valve seat is toward the solenoid end of the casting. Tighten the retainer firmly but do not use force. Install a new spacer and nozzle and tighten. Insert the valve plunger in the other end of casting and check it for free movement, then place spring, gasket, sealing disc and solenoid cup on the casting and reinstall three screws, which must be tightened evenly to insure a good seal.
Insert coil retainer gasket in bottom of coil retainer. Insert coil assembly so that the terminal fits down into the cut-out portion of retainer, and ground terminal is directly over screw hole at the top. Install cover on retainer and tighten screw securely. Position the gasket over the louver plate.
NOTE: The step on the inside portion of the gasket must contact the outer flange of louver and tapered portion of gasket must face the mixer. Position louver plate and mixer assembly with gasket over nozzle. Align three screw holes and spark plug hole with their respective holes in the burner casting. Install three lock-washer screws in louver plate and tighten finger tight. Tighten screws to apply even pressure to the nozzle.
Adjust the spark plug gap to .085 inch. Install spark plug gaskets on spark plug, (concave side of gaskets against the ball portion). Carefully insert the spark plug through the opening in housing and through louver plate. Make certain that the guide slot of spark plug
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