Such discontinuity is ensured by the contacts of the breaker-distributor (Fig. 16).
The contacts work well only with normal gaps between them (0.37-0.43 mm) and sufficient pressure when pressing them against each other (spring force 5.4 N), and uniform wear of the contacting surfaces. The engine power depends on the breaker contacts, or rather on their condition and the gaps between them.
The role of contacts is unnoticeable, and this is often the reason for inattention to them. Meanwhile, it is the gap between the contacts that sets the strength of the spark. The process at the moment of closing the breaker contacts. If the gap is large, i.e. more than 0.43 mm, the time of the closed state of the contacts decreases, and therefore, the current in the ignition coil cannot reach the maximum voltage. And a weak current cannot ensure the appearance of a strong spark.
At low (less than 0.37 mm) the gap between the contacts the result is similar, as the current finds a "loophole" in the form of an arc and hurries to "hide". It has been noted that there is a certain tendency to reduce the gap during operation. In this case, unpleasant phenomena arise, such as an increase in fuel consumption with a simultaneous deterioration in the vehicle's responsiveness.
It has been experimentally established that reducing the gap between contacts by only 0.08–0.1 mm (this corresponds to a change in the ignition timing by 8–10°) leads to an increase in gasoline consumption by 1 l/100 km.
Usually, gaps are adjusted and the condition of the contact surfaces is checked. The necessary equipment is: a starting handle or a special key, a feeler gauge for ignition devices (you will find it in the small tool bag) and a simple key made by yourself (Fig. 17). This key will be of great help when unscrewing the screws that secure the contacts. In extreme cases, such a key can be replaced by a screwdriver.
With the ignition distributor cover removed, use the starting handle to turn the crankshaft until the contacts (see fig. 16) the breaker will open; loosen screw 4 and move contact post 3 using a screwdriver inserted into groove 5 to the required gap (measure with a feeler gauge), and tighten the screw until it stops. If the contacts are adjacent to each other over their entire area, it is enough to wipe them with a napkin soaked in gasoline. It is worse when the contacts wear unevenly. In this case, prompt intervention is required and, as an additional tool, a "velvet" thin file. It should be noted that adjusting the gaps using a feeler gauge is performed very inaccurately, especially when it comes to such delicate operations as adjusting the gaps between the breaker contacts. The feeler gauge is not able to take into account the uneven wear of the contacts, and these "little things" are very significant. That is why at service stations this operation is performed with a device that controls the angle of the closed state of the contacts.
Similar devices have already appeared on the market. They are still expensive, but "thinking" car enthusiasts have already solved this problem. The idea of the innovator from Ivano-Frankivsk is simple: there are marks 3 on the body of the breaker-distributor (Fig. 18). The division value between the marks is 5°. Arrow 2 is secured with a screw that locks rotor 1.
A control lamp is required for operation, which is connected with one end to terminal 4 of low voltage, and the other to the "ground". Turning the crankshaft with the starting handle or a special key, note the angle at which the arrow deviates from the moment the lamp is turned on or off. For reference: when the ignition is on, the lamp flashes when the contacts open and goes out when they close.
[The text is copied from the online resource vazbook]
It should be remembered that on Zhiguli cars the angle of the closed state should be 55±3°, open 35±3°. The sum of these angles is 90±1°. It remains to install the cover with high-voltage wires in its place.
Please note: the slightest distortion of the cover and rotor 1 will immediately break it.
Few people, even experienced and thrifty car enthusiasts, have seriously thought about the question: what causes excess fuel consumption and how to try to reduce it with available means. For example, studies show that if the adjustment in a conventional battery ignition system is violated, the average fuel consumption increases by 4-6%. Despite the fact that the breaker is a simple device and its adjustments are quite simple, it requires close attention.
The condition of the breaker contacts is of great importance. They oxidize and corrode. Unevenness forms on their working surfaces. Repeated cleaning leads to the need to replace them. Most car enthusiasts do not pay attention to the contacts at all. The engine starts and that's it. And so these cars run from maintenance to maintenance, consuming significantly more fuel than they should.
At one time it was fashionable to install various imported and homemade electronic systems on cars. The contacts became "easier" because the current passing through them decreased by 5-10 times, erosion disappeared, but new problems appeared: the low current could not overcome various types of film deposits. And the fashion passed.
Soon a truly radical solution was found - replacing the mechanical interrupter with a contactless sensor. For those who want to reduce contact oxidation and reduce their gasoline costs today, we can recommend purchasing a contactless ignition kit BESZ-I, manufactured by the Kievpribor production association.
In addition to its main functions, the BESZ-I simultaneously serves as an anti-theft device, provides a multi-spark mode when starting the engine and allows the use of various electrical devices operating at 127 V from the vehicle's on-board network.