Nowadays it cannot be found under the hood of petrol engines any more. Mechanical parts were substituted by electronic ones. The distributor formed the heart of the ignition system. Here the most important adjustments had to take place and most sources of error were also found in this part.
Primary circle and secondary circle meet each other in the simple coil ignition in the distributor. On top the distributor cap with the rotor arm. It is connected via the middle pin (high-tension cable 4) and a spring-loaded coal with the ignition coil. It distributes the high voltage by its rotation to the in each case nearest pin via plug lead to the single spark plugs according to the firing order. A gap must be overcome, because it does not touch the pins.
One floor below we are in the middle of the primary circle. If there is just one distributor and one breaker, the interrupter contact is operated as often with one rotation as there are cylinders in the engine. It controls via terminal 1 in the ignition coil the ignition release. Again one floor down this cam is twisted with rising revs compared to the axle drive shaft by the centrifugal governor.Even further down there is the clamp device which allows by releasing and twisting the whole distributor, the setting of the ignition time, and there is the skew drive gear which is driven by a similar one mostly by the camshaft.
Let us commence with an easier component, the distributor cap. If you want to replace this part, you have to pay attention to the fact that the single plug leads must be put back to exactly the same spot at which they were with the old cap. Therefore, you should hold the new cap next to the old one. Because it is still possible to falsely turn it around by 180 °, it would be favourable to mount the new cap before the replacement onto the old distributor (screwing or clipping). Only then you can be sure that the plugging in of the pins is correct.
Before you exchange a complete distributor, the results should be considered. The new one must be adjusted before tightening. This does not work by marking the old one and transferring these index marks onto the new one. Rather, the new distributor must be twisted - mostly with a stroboscope lamp - before tightening it at a predefined engine speed in such a way that certain notches in the flywheel or in the V-belt pulley match. In addition you need most often also the data from the manufacturer. Only in special cases you could determine the data of the old distributor by a measurement and then transfer them onto the new one. Summarising, before loosening the distributor consider what you are doing!