Note: On engines equipped with MMFD Mono-point G5/6 or Motronic M1.3 engine management systems the ignition timing is controlled by the system ECU and cannot be adjusted.

XV, XW and XY series engines 1 To set the ignition timing statically so that the engine can be started first remove No 2 spark plug and turn the engine in the normal rotational direction until pressure is felt - indicating that the piston is commencing the compression stroke. The pressure can be felt using a suitable wooden rod or a piece of cork placed over the spark plug hole.

2 Remove the plastic cover from the timing aperture then continue turning the crankshaft until the mark on the flywheel is opposite the BTDC mark on the timing plate (see illustration).

8.2 Timing plate marks on XV, XW and XY series engines

3 Check that the distributor rotor arm is facing the No 2 HT lead segment position in the distributor cap. To do this, remove the cap and mark the outside in line with the segment, then put it back on the distributor noting which way the rotor arm is facing.

4 If necessary, loosen the mounting nuts and turn the distributor body to bring the segment and rotor arm in line, then tighten the nuts.

Refit No 2 spark plug.

5 Run the engine to normal operating temperature then stop it and connect a tachometer and stroboscopic timing light as described in the instrument manufacturer’s instructions. If the HT pick-up lead of the timing light is connected to the HT lead on the ignition coil it is possible to detect any discrepancy between the firing of Nos 1 and 4 and Nos 2 and 3 cylinders since there are two diametrically opposite timing marks on the flywheel. However, the pick-up lead may be connected to any one of the spark plug HT leads, in which case only one of the flywheel timing marks will be used.

6 Disconnect and plug the vacuum pipe at the distributor vacuum advance unit.

7 Run the engine at the specified speed and point the timing light into the timing aperture.

The single mark on the flywheel should be aligned with the BTDC mark on the timing plate (see illustration).

8.7 Ignition timing adjustment on XV, XW and XY series engines

A Using spark plug HT lead B Using ignition coil HT lead

If the ignition coil HT lead has been used (see paragraph 5), and there is wear in the distributor, there will be two marks visible on the flywheel close to each other. In this case the mid-point between the two marks should be aligned with the BTDC mark on the timing plate.

8 If adjustment is necessary, loosen the distributor mounting nuts and rotate the distributor body as required. Tighten the nuts on completion.

9 The operation of the centrifugal advance weights in the distributor can be checked by increasing the engine speed with the timing light pointing in the timing aperture and observing that the mark on the flywheel advances from its initial position.

10 To check the vacuum advance unit, run the engine at a fast idle speed and reconnect the vacuum pipe. The flywheel mark should again advance.

11 Stop the engine, disconnect the tachometer and timing light and reconnect the vacuum pipe. Refit the timing aperture cover.

XU series engines
12 To set the ignition timing statically so that the engine can be started, first remove No 1 spark plug (nearest the flywheel) and turn the engine in the normal rotational direction until pressure is felt - indicating that the piston is commencing the compression stroke. The pressure can be felt using a suitable wooden rod or piece of cork placed over the spark plug hole.

13 While looking into the timing aperture in the clutch housing/transmission casing, continue turning the crankshaft until the single mark on the flywheel is opposite the BTDC mark on the timing plate (see illustration).

8.13 Initial static ignition timing on XU series engines

a Single flywheel mark b BTDC mark on timing plate

14 Check that the distributor rotor arm is facing the No 1 HT lead segment position in the distributor cap. To do this, remove the cap and mark the outside in line with the segment, then put it back on the distributor noting which way the rotor arm is facing.

15 If necessary, loosen the mounting nuts and turn the distributor body to bring the segment and rotor arm in line, then tighten the nuts. Refit No 1 spark plug.

16 Run the engine to normal operating temperature then stop it and connect a tachometer to it.

17 Disconnect and plug the vacuum pipe at the distributor vacuum advance unit.

18 Disconnect and remove the air cleaner inlet duct then connect a stroboscopic timing light to the engine as described in the timing light manufacturer’s instructions, and with the HT pick-up lead connected to No 1 spark plug HT lead.

19 On early models, run the engine at 3500 rpm and point the timing light into the timing aperture. The double mark on the flywheel should be aligned with the TDC mark on the timing plate; indicating that the ignition is advanced by 30° (see illustration).

8.19 Dynamic ignition timing on XU series engines

a Double flywheel mark b TDC mark on timing plate

On engines without double timing marks, refer to the Specifications for the relevant ignition timing setting and engine speed, then check that the single mark on the flywheel is aligned with the appropriate mark on the timing plate.

20 If adjustment is necessary, loosen the distributor mounting nuts and rotate the distributor body as required. Tighten the nuts on completion.

21 Check the centrifugal and vacuum advance characteristics of the distributor, as described in paragraphs 9 and 10.

22 Stop the engine, disconnect the tachometer and timing light then reconnect the vacuum pipe and air cleaner inlet duct.

TU series engines
23 To set the ignition timing statically so that the engine can be started, refer to the procedures contained in paragraphs 12 to 15 above.

24 To check the ignition timing, a stroboscopic timing light will be required. It is also recommended that the flywheel timing mark is highlighted as follows.

25 Remove the plug from the aperture on the front of the transmission clutch housing.

Using a socket and suitable extension bar on the crankshaft pulley bolt, slowly turn the engine over until the timing mark (a straight line) scribed on the edge of the flywheel appears in the aperture. Highlight the line with quick-drying white paint - typist’s correction fluid is ideal (see illustrations).

8.25a On TU series engines, remove the plug from the transmission housing . . .

8.25b . . . to reveal the timing plate and flywheel timing mark (arrowed)

26 Start the engine, allow it to warm up to normal operating temperature, and then stop it.

27 Disconnect the vacuum hose from the distributor diaphragm, and plug the hose end.

28 Connect the timing light to No 1 cylinder spark plug lead (No 1 cylinder is at the transmission end of the engine) as described in the timing light manufacturer’s instructions.

29 Start the engine, allowing it to idle at the specified speed, and point the timing light at the transmission housing aperture. The flywheel timing mark should be aligned with the appropriate notch on the timing plate. The numbers on the plate indicate degrees Before Top Dead Centre (BTDC).

30 If adjustment is necessary, slacken the two distributor mounting nuts, then slowly rotate the distributor body as required until the flywheel mark and the timing plate notch are brought into alignment. Once the marks are correctly aligned, hold the distributor stationary and tighten its mounting nuts.

Recheck that the timing marks are still correctly aligned and, if necessary, repeat the adjustment procedure.

31 When the timing is correctly set, increase the engine speed, and check that the flywheel mark advances to beyond the beginning of the timing plate reference marks, returning to the specified mark when the engine is allowed to idle. This shows that the centrifugal advance mechanism is functioning.

Reconnect the vacuum hose to the distributor, and repeat the check. The rate of advance should significantly increase if the vacuum diaphragm is functioning correctly.

32 When the ignition timing is correct, stop the engine and disconnect the timing light.