MUFFLER AS 1278594 - Caterpillar

3500 Series EnginesThe complete procedure to check and adjust the fuel injector timing is given in the Testing and Adjusting sections of the following Service Manuals for 3500 Series Engines: Pages 59, 60 of Form SENR2374 for 3500 Series Marine Engines, Pages 75, 76 of Form SENR2352 for 3500 Series Industrial Engines, Pages 59, 60 of Form SENR2362 for 3500 Series Generator Set Engines, and Pages 3-24, 3-25 of Form SEBR0548 for Vehicular Engines. Additional information is given in this article to make sure that the dial indicator readings are interpreted correctly by the service technician.
Dimension (A), shown in the illustration, is the actual fuel timing dimension of the unit injector. It is the distance from the top surface of the injector follower to the injector body. The body is used as a reference surface for measurement. If this dimension is not within the specifications given in the Fuel Setting and Related Information microfiche, the injection timing will be either advanced or retarded.
The specifications for the fuel timing dimension are not the same for all 3500 Series Engines. For example, Dimension (A) is 87.00 .20 mm (3.425 .008") on a correctly timed injector used in a current production high speed engine (1301 to 1800 rpm). On a low speed engine (900 to 1300 rpm) Dimension (A) is 87.64 .20 mm (3.450 .008"). The above dimensions are used her as examples only and may not be correct for future production engines. The correct fuel timing dimension for the engine that is being inspected must be obtained from the Fuel Setting and Related Information microfiche before any adjustment is made to Dimension (A).
Find the correct fuel timing dimension from the Fuel Setting and Related Information microfiche. Use the chart below to find the dial indicator setting that corresponds to the specified timing dimension. Use the 6V3117 Set Gauge to set the dial indicator to the desired reading.
After the dial indicator has been correctly set, place the indicator with the attached timing fixture on the injector follower surface. The roller on the lifter assembly must be on the base circle of the cam lobe and not on any other portion of the cam lobe. The correct position of the lifter assembly roller is shown in the illustration. Refer to the appropriate Service Manual for the procedure to correctly position the cam follower.
If the injector is correctly timed, the dial indicator will show a reading of 0.00 .20 mm. If the dial indicator gives a reading of + .21 mm or greater, this means the stem of the indicator has moved toward the dial indicator and Dimension (A) is shorter than it should be. Since the injector plunger is directly connected to the injector follower, a reading of + .21 mm means the injector plunger has moved too far down the injector barrel toward the combustion chamber. Timing will be too far advanced in this case.
If the dial reading is - .21 mm or less, Dimension (A)