Contents: Bosch spark plugs ↓ Beru candles ↓
Spark plugs consist of a central electrode, an insulator with a housing and a side electrode (ground electrode). The central electrode is installed in the insulator, the insulator is firmly connected to the housing. A spark occurs between the central and side electrodes. The quality of the spark plugs determines such engine parameters as readiness to start, stability of operation at idle speed, throttle response and maximum speed. Therefore, you should use the type of spark plugs specified by the engine manufacturer. It should be borne in mind that spark plugs of a different type have different thermal characteristics (heat rating).
The glow number determines the degree of heat resistance of the spark plug. The lower the glow number of the spark plug, the higher its heat resistance. This means that the spark plug dissipates heat better, thereby reducing the likelihood of pre-ignition (detonation). The disadvantage of a spark plug with high heat resistance is its higher self-cleaning temperature. This leads to more intense carbon formation, especially when the engine does not reach its operating temperature during operation (urban driving, short distances in winter). As a rule, "cold" candles (heat rating starting from 06) are installed on "hot" engines, i.e. on engines that require high power output.
The heat rating is indicated in the spark plug marking. The spark plug marking has the following structure:
Bosch spark plugs
Example of marking:
| W | R | 7 | D | WITH |
| 1 | 2 | 3 | 4 | 5 |
(1) W=thread M14x1.25 with flat sealing surface, spanner size 21; F=M14x1. 25 thread with flat sealing surface, turnkey size 16; M=thread M18x1.5 with flat sealing surface, key size 25; H=thread M14x1.25 with conical sealing surface, spanner size 16; D=thread M18x1.5 with conical sealing surface, key size 21.
(2) R=with a noise suppression resistor, this indicator does not affect the performance of the spark plug.
(3) Heat rating. The heat rating is in the range from 06 ("cold") to 10 ("hot"). The number 7 corresponds to the old designation of the heat rating, 17 corresponds to 200.5-225, etc.
(4) A=thread length 12.7mm, without protrusion
B=thread length 12.7 mm, with protrusion
C=thread length 19mm, without protrusion
D=thread length 19mm with thermal housing protrusion
(5) central electrode material: if no data available = chromium-nickel alloy; C = electrode material composite, consists of nickel and copper; S = silver central electrode; P = platinum; O = standard spark plug with reinforced central electrode.
Thanks to the copper core (Cu) on the central electrode and even more thanks to the silver central electrode, it increases the thermal conductivity of the spark plug and its heat resistance.
Beru candles
Example of notation:
| 14 | R | 7 | D | U |
| 1 | 2 | 3 | 4 | 5 |
(1) thread diameter in mm, here M14x1.25.
(2) design feature, for example,? means conical coupling, R means the presence of a noise suppression resistor.
(3) heat rating (like Bosch).
(4) thread length (like Bosch)
(5) electrode material, for example, U - with a copper core.
Production models of TOYOTA COROLLA cars are usually equipped with NGK or Nippondenso spark plugs. Different manufacturers use different candles. When replacing standard candles, you can use Bosch and Beru candles.