Opel Corsa B 1993–2000 Service and Repair Manual: Ignition timing - adjustment

Models using leaded (4-star) petrol

1. For prolonged engine life, efficient running performance and economy it is essential for the fuel/air mixture in the combustion chambers to be ignited by the spark plugs at precisely the right moment in relation to engine speed and load. For this to occur the ignition timing must be set accurately and should be checked at the intervals given or wherever the position of the distributor has been altered. To make an accurate check of the ignition timing it is necessary to use a stroboscopic timing light, whereby the timing is checked with the engine running at idling speed.

2. If the distributor has been removed, or if for any reason its position on the engine has been altered, obtain an initial setting to enable the engine to be run, as described in Section 6. Also make sure that the contact breaker points gap or dwell angle is correctly set.

3. To check the timing, first highlight the timing marks using white chalk or quick-drying paint. The marks are a notch on the crankshaft pulley and a raised mark on the timing cover. When they are aligned the engine is at the specified number of degrees BTDC when the marks are aligned, not TDC.

4. Run the engine up to its normal operating temperature and then switch off.

5. Connect a timing light to the spark plug lead of No 1 cylinder, following the manufacturer's instructions.

6. With the engine idling, point the timing light at the timing marks. The marks will appear stationary, and if the timing is correct, they will be aligned.

7. If the marks are not aligned, slacken the distributor clamp bolts or retaining nuts and move the distributor body slowly in one direction or the other until the marks line up.

Tighten the clamp bolt or retaining nuts and check that the setting has not altered.

8. Open the throttle slightly and note the movement of the timing marks. If the centrifugal advance in the distributor is working correctly the marks should appear to move away from each other as the engine speed increases. The same should happen if suction is applied to the vacuum advance pipe after disconnecting it from the carburettor, indicating that the distributor vacuum unit is satisfactory.

9. After checking the timing, switch off the engine and disconnect the timing light, if removed, refit the vacuum pipe to the carburettor.

Models using unleaded petrol

Early (pre February 1985) models

10.On models produced up to February 1985, no adjustment of the ignition timing is necessary if the vehicle is to be run on unleaded fuel.

Later (February 1985 on) models

11. All models produced after February 1985 are designed to run on unleaded, but the manufacturers state that the ignition should be retarded by 3º, to 7º BTDC.

12. The crankshaft pulley only has one timing mark (10º BTDC), so it will be necessary to make additional marks to accurately retard the ignition.

13. Turn the engine by means of the crankshaft pulley bolt, or by engaging top gear and pulling the car forward, until No 1 piston is at TDC on the firing stroke. This can be felt by removing No 1 spark plug and feeling for compression with your fingers as the engine is turned. The precise TDC point will have to be determined using a blunt probe (such as a knitting needle) inserted through No 1 spark plug hole.

14. Make a mark on the crankshaft pulley in alignment with the timing mark, or pointer, on the engine.

15. The original pulley mark indicates 10º BTDC, and the new mark TDC. Using these two markings, measure out a make a third mark on the pulley in the 7ºBTDC position.

16. Using the new timing mark, adjust the ignition timing as described in paragraphs 4 to 7. If detonation occurs, it may be necessary to retard the ignition timing even further; some experimentation may be worthwhile to achieve satisfactory running.