RACE-BEARING 1912687 - Caterpillar

Note: For information on the following topics, see the Service Manual, "Systems Operation/Testing and Adjusting" or see Special Instruction, REHS2558, "Installation and Initial Start-Up Procedure for G3500 A3 Engines".
Adjusting the carburetor
Adjusting the control linkage for the carburetor
Adjusting the exhaust bypassConsult your Caterpillar dealer for assistance.Air/Fuel Ratio
The correct air/fuel ratio is very important for the following considerations:
Margin of detonation
Control of emissions
Achieving optimum service life for the engineIf the air/fuel ratio is not appropriate for the fuel and the operating conditions, a failure of the engine may occur. The service life of the turbocharger, the valves, and other components may be reduced.Fuel Supply Pressure
Fluctuations of the fuel pressure can change the air/fuel ratio. For high pressure gas fuel systems, the maximum fluctuation that is allowed in the fuel pressure is 3.4 kPa (0.50 psi). For low pressure gas fuel systems, the maximum fluctuation that is allowed in the fuel pressure is 1.7 kPa (0.25 psi). Ensure a stable fuel pressure to the engine by installing a second gas pressure regulator prior to the gas pressure regulator on the engine.Gas Pressure Regulator
The gas pressure regulator maintains a pressure differential between the air and the fuel that is supplied to the carburetor. Set the pressure of the fuel supply to a maximum of 1.5 kPa (6 inch of H2O) more than the pressure of the air supply. The gas pressure regulator will maintain the pressure differential in response to changes in the air pressure. If high idle stability is important, lower the differential pressure to 1 kPa (4 inch of H2O). The higher differential pressures will give better engine response to load changes.A water manometer is used to measure the pressure differential. This measurement is taken when the engine is operating at high idle rpm. When a load is applied, the fuel pressure will usually decrease by approximately 0.25 to 0.5 kPa (1 to 2 inch of H2O). If the performance of the gas pressure regulator is erratic, the gas pressure regulator may require service.Temperature of the Fuel Supply
Changes in the temperature of the fuel supply affects the air/fuel ratio. Warmer fuel is less dense than cold fuel. This results in a leaner mixture that causes a noticeable reduction of power. The recommended temperature differential of the air and the fuel is 2.8 °C (5 °F).The maximum fuel temperature depends on the temperature regulator of the aftercooler:
For engines with a 32 °C (90 °F) aftercooler, the maximum temperature of the air/fuel mixture is 38 °C (100 °F).
For engines with a 54 °C (130 °F) aftercooler, the maximum temperature of the air/fuel mixture is 60 °C (140 °F). Consult your Caterpillar dealer for assistance.Temperature of the Air Supply
Changes in the temperature of the air supply affects the air/fuel ratio. In addition to seasonal changes, the air temperature changes overnight. Control of the temperature in the engine room will help to maintain the air/fuel ratio.To optimize the inlet air temperature, use ducting and a heat exchanger. This will help to avoid exposure to hot