The picture shows the complete lower part of the distributor including condenser and vacuum advance unit. In the distributor, one can see the four-fold cam for the four-cylinder and the contacts. As we are dealing with a French product here, one notices that the anvil is very much larger, in comparison with the hammer. This was one possibility, of reducing the contact-burning by distributing the contact over a larger area.
In actual fact, no solution was found for the problem of contact-burning. It was not enough that the condenser cut the electric arc at the beginning of the contact opening. Because up to 4 Amperes of current had to be switched, it was easy for a material-fragment (Wolfram) to be baked hard onto the opposite side. Thereby, the contact-gap and the dwell angle were changed. The performance dropped and the pollution portion of the exhaust gas as well as the consumption increased.
To reduce this, the hammer not only came down on the point but carried out a sliding movement as well. This was to prevent the material deposit on the opposite side. Another specific feature of this distributor, is the adjustable spring tension of the vacuum advance adjustment. Thereby, the influence of the load-dependent ignition adjustment could be varied.
Nowadays, the problems concerning contact breakers can only be of interest to veteran-car fans. Even if they are perectly adjusted, problems can still occur after a short time. E.g., the multiple cam be be too rough, causing it to slowly wear down it's plastic partner. Regrinding with a very fine emery cloth can help in some cases. The application of a little grease afterwards, goes without saying.
A lot more serious, is when the shaft has all together too much play. This can be recognized if the dwell angle, when giving gas, is not reduced, which would be normal, but on the contrary, it increases. In this case, the only solution is to replace the entire unit. By the way, it must not always be the exact model for this particular engine. There is also the possibility of replacing it with an available vacuum advance unit, then, by carefully bending the spring in the centrifugal adjustment, the timing-curve for a particular engine can (to a certain degree) be produced. 09/09