Ignition timing - adjustment

Ignition systems / Ignition timing - adjustment

Note: The engine should be at normal operating temperature to ensure correct results
Note: Accurate checking and setting of the ignition timing is only possible using a special instrument connected to the flywheel TDC sender unit through the aperture in the top of the gearbox be//housing. This will not normally be available to the home mechanic, so a method using a stroboscopic timing light is described below. It should be noted that this only provides an approximate setting - it is recommended that the vehicle be checked by a VW dealer at the earliest opportunity.

1 Disable the engine by unplugging the multiway Hall sender connector from the distributor.

2 Using a spanner or socket and wrench on the crankshaft pulley, turn the engine manually until the crankshaft pulley timing mark (a notch cut into the edge of the pulley) becomes visible. Clean the edge of the pulley, then highlight the timing mark with chalk or a dab of white paint. On G40 models, there are two marks: the timing mark has a ‘Z’ stamped next to it on the crankshaft pulley (the TDC mark is indicated by an ‘0’).

3 Reconnect the distributor multiway plug, then connect the stroboscopic timing light to the engine in accordance with the manufacturer’s instructions, so that it is triggering from the No 1 cylinder HT lead.

4 Start the engine and run it at idling speed.

Direct the beam from the timing light at the pointer protruding from the timing belt cover.

The stroboscopic effect should ‘freeze’ the motion of the crankshaft pulley and the highlighted timing mark. If the mark appears to be moving back and forth, this may be due erratic idling - check that all of the cars electrical accessories are switched off and that the auxiliary cooling fan is not running.

The engine should be at normal operating temperature, but the idle speed may be become unstable if it is particularly hot day and the engine has been idling for some time.

5 The highlighted timing mark should appear to be stationary and aligned with the pointer on the timing belt cover (see illustrations). If they are not aligned, the basic ignition setting requires adjustment.

5.5a Ignition timing marks - all models except G40

5.5b Ignition timing marks - G40 models

6 To adjust the basic ignition timing setting, first switch off the engine, to avoid the risk of a getting a shock from the HT voltage. Refer to Section 4 and slacken the distributor retaining bolts. Note: Mark the relationship between the distributor body and the cylinder head with a dab of paint, before adjustment is attempted. This gives a reference point that can be reverted to if the timing setting is lost.

7 Turn the distributor by a small amount clockwise to advance (or anti-clockwise to retard) the ignition timing. Tighten the bolts lightly and repeat the timing light test.

Continue until the timing setting is correct, then tighten the distributor bolts to the specified torque.