Opel Corsa B 1993–2000 Service and Repair Manual: Contact breaker points - gap and dwell angle adjustment

1. To adjust the contact breaker points so that the correct gap is obtained, first undo the two distributor cap retaining screws, lift off the cap and withdraw the rotor arm from the distributor shaft. At this stage it is a good idea to clean the inside and outside of the cap and inspect its condition. It is unlikely that the four segments inside the cap will be badly burned or corroded, but if they are the cap must be renewed. If only a small deposit is on the segments, it may be scraped away using a small screwdriver.

2. Push in the carbon brush located in the centre of the cap several times to ensure that it moves freely. The brush should protrude by at least 6 mm.

3. Gently prise the contact breaker points open to examine the condition of their faces. If they are rough, pitted or dirty it will be necessary to remove them to enable new points to be fitted.

4. Assuming that the points are in a satisfactory condition, or that they have been renewed, the gap between the two faces should be measured using feeler blades as follows.

5.Pull off the plug leads, after marking them to ensure correct refitment, and then remove the spark plugs.

6.With the transmission in gear and the handbrake released, slowly pull the car forward, while at the same time watching the distributor, until the heel of the contact breaker arm is on the peak of one of the four cam lobes. A feeler blade equal to the contact breaker points gap, as given in the Specifications, should now just fit between the contact faces (see illustration). Make sure that the feeler blade is clean - if the contact faces are contaminated with oil or grease, the LT current will be greatly reduced and malfunction will result.

Checking the contact breaker points gap using a feeler blade

7. If the gap varies from this amount, slacken the contact breaker plate retaining screw and move the breaker plate in or out to achieve the desired gap. The plate can be easily moved with a screwdriver inserted between the notch in the breaker plate and the two adjacent pips in the distributor baseplate.

8. When the gap is correct, tighten the retaining screw and then recheck the gap.

9. Refit the rotor arm, distributor cap, spark plugs and leads.

10. If a dwell meter is available, a far more accurate method of setting the contact breaker points gap is by measuring and setting the distributor dwell angle.

11. The dwell angle is the number of degrees of distributor cam rotation during which the contact breaker points are closed, ie the period from when the points close after being opened by one cam lobe until they are opened again by the next cam lobe. The advantages of setting the points by this method are that any wear of the distributor shaft or cam lobes is taken into account, and also the inaccuracies of using a feeler blade are eliminated. In general, a dwell meter should be used in accordance with the manufacturer's instructions. However, the use of one type of meter is outlined as follows.

12. To set the dwell angle, remove the distributor cap and rotor arm and connect one lead of the dwell meter to the '+' terminal (15) on the coil and the other lead to the '-' terminal (1 ) on the coil.

13. Whilst an assistant turns on the ignition and operates the starter, observe the reading on the dwell meter scale. With the engine turning on the starter the reading should be as stated in the Specifications.

Note: Fluctuation of the dwell meter needle indicates that the engine is not turning over fast enough to give a steady reading. If this is the case, remove the spark plugs and repeat the checks.

14. If the dwell angle is too small, the contact breaker point gap is too wide, and if the dwell angle is excessive the gap is too small.

15. Adjust the contact breaker points gap, using the method described in paragraph 7, until the correct dwell angle is obtained.

16. When the dwell angle is satisfactory, disconnect the meter and refit the rotor arm, distributor cap and, if removed, the spark plugs and leads.

17. Check the ignition timing.