Spark plugs — general information

The spark plug consists of an insulator, a housing, a center electrode and a ground electrode. The mass electrode is tightly fixed in the insulator. The insulator is rigidly connected to the housing. An ignition spark jumps between the central and ground electrode, which ignites the air-fuel mixture.

Ease of starting, idling performance, acceleration and top speed depend on the spark plug. Based on this, it is impossible to deviate without reason from the type of candles prescribed by the manufacturer, which is determined by the glow number. The glow number indicates the degree of heat load of the spark plug in the engine under certain operating conditions.

Spark plugs for the engine are selected so that they reach the self-cleaning temperature under various operating conditions. The lower the glow number of a spark plug, the higher its resistance to glow ignition and the lower its resistance to fouling. The higher the glow number of a spark plug, the lower its resistance to glow ignition and the higher its resistance to fouling.

The heat number of a spark plug is contained in the spark plug code. The code is decrypted as shown below.

Bosch spark plug

F	R	G	D	U	R
1	2	3	4	5	6

1.

• W - thread M14 x 1.25 with a flat fit, SW21;
• F - thread M14x1.25 with a flat fit, SW16;
• M - thread 18 x 1.5 with a flat fit, SW25;
• H - thread M14 x 1.25 with a cone fit, SW16;
• D - thread M18 x 1.25 with a cone fit, SW 21;
• SW is the key size.

2. R - with noise suppression resistor. The operation of the ignition system is not affected.


3. Heat number. The incandescent scale has designations from 06 ("cold") up to 13 ("hotter"). In this case, the number 7 corresponds to the old incandescent number 175 (old designation), 6-200, 5-225, etc.

4.

• A - thread length 12.7 mm, normal spark discharge trajectory;
• B - thread length 12.7 mm, elongated spark discharge trajectory;
• C - thread length 19 mm, normal trajectory of the spark discharge;
• D - thread length 19 mm, elongated spark discharge trajectory;
• DT - thread length 19mm, elongated spark discharge trajectory, 3 ground electrode;
• L - thread length 19 mm, highly elongated spark discharge trajectory.

5. Electrode material of the central electrode: Cr-Ni alloy;

• С – central electrode from Ni-Cr compound;
• S – silver central electrode;
• Р – platinum central electrode;
• O - standard spark plug with a reinforced center electrode.

6. R \u003d 1 kOhm, resistance to burning, X - distance between the electrodes 1.1 mm.

Thanks to the inclusions of copper (Xi) into the central electrode and, even more, when using a silver electrode, the thermal conductivity increases, and hence the thermal load. The advantage of a spark plug with a platinum center electrode is high sparking ability, low wear and a wide glow range.

BERU spark plug

14	F	G	D	U	R
1	2	3	4	5	6

1. Thread diameter in mm, here M14 x 1.25.

2. Design, for example, K - for a cone fit, F - for a flat fit, SW16, R with an interference suppression register.

3. Heat number. The incandescent scale has designations from 06 ("cold") up to 13 ("hotter"). In this case, the number 7 corresponds to the old incandescent number 175 (old designation), 6-200, 5-225, etc.


4.

• A - thread length 12.7 mm, normal spark discharge trajectory;
• B - thread length 12.7 mm, elongated spark discharge trajectory;
• C - thread length 19 mm, normal trajectory of the spark discharge;
• D - thread length 19 mm, elongated spark discharge trajectory;
• OT - thread length 19mm, elongated spark discharge trajectory, 3rd electrode of mass;
• L - thread length 19 mm, highly elongated spark discharge trajectory.

5. Electrode material, for example, with U copper inclusions.

6. R = 1 kOhm, burn resistance.