893680T03 Mercury GEAR HOUSING ASSEMBLY, Complete - Short

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Timing Gears (1) Idler gear (2) Camshaft gear (3) Fuel injection pump drive gear (4) Crankshaft gear
Improper fuel injection timing can cause poor engine performance. The engine timing gears have a reference mark on each gear. The No. 1 cylinder is at the top center position when the two numbers on the fuel injection pump gear, the camshaft gear and the crankshaft gear straddle a tooth on the idler gear. The fuel injection pump drive gear turns the camshaft of the fuel pump. Rotating the fuel pump relative to the pump gear changes the fuel injection timing.Note: This engine is not timed with a pin and this engine has an idler gear with an odd number of teeth. Do not rotate the engine if the fuel injection pump is removed. If you rotate the engine, the engine should be timed by Step 7. The gears must be aligned by using the timing marks once the front housing is removed. Mark the teeth with a paint stick. Reinstall the fuel injection pump by meshing the marked teeth.
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Fuel Injection Pump Timing Mark (1) Timing marks (2) Timing marks
Timing marks (1) and (2) on the fuel injection pump indicate the pump position relative to the timing gear. Each mark on the scale represents a change in timing of six degrees.
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Adjusting Fuel Injection Pump Timing (X) Direction of advancing timing (Y) Direction of retarding timing
Loosen the retaining bolts. Rotating the fuel pump toward the engine retards injection timing while rotating the fuel pump away from the engine advances injection timing.
To check the fuel injection timing, disconnect the fuel injection line from the fuel injection pump. Loosen the clamp and remove the delivery valve holder. Remove the valve spring and the stopper from the delivery valve holder. Replace only the delivery valve holder. Install a new fuel line to the delivery valve holder.
Turn the crankshaft until the No. 1 piston is approximately 60 degrees BTC on the compression stroke.Note: Check the valve lash with the No. 1 cylinder at the top center position. This ensures that the cylinder is on the compression stroke and that the cylinder is not on the exhaust stroke.
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Crankshaft Pulley Timing Marks
The crankshaft pulley contains a scale that has a range of 0 degrees to 40 degrees. Each mark on the scale represents a 5 degree crankshaft rotation.
Use a suitable container to catch any fuel that might spill. Clean up any spilled fuel immediately.
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Checking for fuel flow (6 cylinder engine) (3) Fuel priming pump
Operate the fuel priming pump. Rotate the engine crankshaft until the fuel stops flowing. Read the number of the timing mark on the crankshaft pulley that is indicated. The fuel timing advance should be 8 degrees BTC or the fuel timing advance should be 20 degrees BTC for the 3064 Engine. The fuel timing advance should be 10 degrees BTC or the fuel timing advance should be 16 degrees BTC for the 3066 Engine. Refer to the Engine Information Plate on the valve cover for fuel injection timing. Refer to the Technical Marketing Information (TMI) for other technical data. To correct the fuel injection timing, rotate the fuel pump. Refer to Step 3.