Timing Advance Unit
(1) Gear on camshaft for fuel injection pump. (2) Timing advance unit. (3) Camshaft for the engine.
Timing Advance Unit
(4) Weights. (5) Springs. (6) Slides.
The timing advance unit (2) is installed on the front of the camshaft (3) for the engine. The timing advance unit (2) drives the gear (1) on the camshaft for the fuel injection pump. This gear is the drive for the camshaft for the fuel injection pump.
The weights (4) in the timing advance are driven by two slides (6) that fit into notches made on an angle in the weights. The slides (6) are driven by two dowels which are in the drive gear for the engine camshaft. As centrifugal force (rotation) moves weights (4) outward against the force of springs (5), the movement of the notches in weights (4) will cause the slides to make a change in the angle between the timing advance gear and the two drive dowels in the drive gear for the engine camshaft. Since the timing advance unit drives the gear (1) on the camshaft for the fuel injection pump, the fuel injection timing is also changed.
The timing advance unit will change the timing 5 degrees. This change starts at approximately low idle rpm and is operating up through the rated speed of the engine. No adjustment can be made to the timing advance unit.
Lubrication oil for the timing advance unit comes from drilled holes that connect with the front bearing for the engine camshaft.
Gear And Weight Assembly For Low Emissions Engines
Low emissions engines do not have a timing advance. The use a “blocked” timing advance where the weights are blocked from sliding. This provides fixed timing, but retains the gear train torsional load dampening provided by the advance mechanism for longer gear teeth life.