The contact points require periodic replacement regardless of which type of distributor is fitted to your Series Land Rover. However, over the years, wear and tear takes its toll on other component parts of the distributor that are subject to rapid movement. The more wear there is, then the less likely the ignition timing is going to be either consistent or correct. Correct ignition timing is critical for good fuel economy and good engine performance.
The most effective way of checking the distributor for
potential faults is to remove it from the Land Rover, but then you need to be able to re-set the ignition timing once the servicing is complete. Servicing can however be performed with the distributor in place, though accessibility can be an issue.
1. Check for cracks inside the distributor cap, corrosion on the distributor cap terminals(inside and outside) and sufficient tension in the central carbon brush spring.
2. The rotor arm should not show signs of wear or burning from electrical arcing. A wrongly sized rotor arm will cause too big a gap and too much arcing (difficult starting problems). The rotor arm gap can be checked by inverting the distibutor cap and holding the rotor upside down centrally inside the cap.
3. Check for lateral and vertical movement of the central distributor shaft. There should be almost none. If present, the timing will not be consistent. The solution is a new distributor or replacement bushings.
The contact points should be correctly gapped (Lucas 0.015in, 0.38mm; Ducelier 0.017in, 0.43mm) and the surfaces should not be pitted.
5. Check the fragile earthing strap is not frayed or damaged and that the wiring on the terminals is similarly not frayed.
6. Sucking through the vacuum pipe should cause the baseplate to rotate. Light lubrication can help here (too much oil can foul the contact points).
7. The red plastic heel in contact with the central shaft should not show signs of wear and the shaft should be smeared with a thin layer of grease on reassembly to prevent this wear.
8. Unless they have been renewed in the last 1000miles it is sensible to renew the contact points and condenser on re-assembly as they are cheap and so important for a Series Land Rover engine's performance(always carry spares for these).
9. Removal of the baseplate for the contact points gives access to the mechanical advance weights. These should be easily displaced when gently moved with a small screwdriver and return to their original positions without sticking. Light lubrication can help restore mobility if needed. In time, the return springs can weaken and can be replaced, if available, otherwise a replacement distributor is needed.