Heat number
Depending on compression and power output, gasoline engines develop quite different temperatures in the combustion chambers. They must match the spark plugs. This property is expressed by the so-called heat number. Index 8 indicates the temperature that the spark plug can withstand, i.e. able to take it away without overheating. If the spark plug gives off too much heat, it will not reach its self-cleaning temperature, which means that the hot spark plug electrodes can free themselves of soot deposits.
Electrode shape
Opel, in its spark plug tests, opted for «frontal electrode extended forward». The central electrode protrudes from the body of the spark plug and is furthermore covered from the front by the outer electrode.
Spark plug thread
The screw-in thread should be 19 mm long, the longest length offered by the trade. The thread diameter is 14 mm.
The combustion chambers in the engine are shaped to ensure proper combustion of the working mixture. The location and depth of screwing of the candle play an important role in this. Therefore, candles cannot be inserted, for example, with two sealing rings.
Spark plugs for Vectra
Opel recommends for 8-valve engines and also for 16V engines spark plugs with part number 12 14 005 or part number 90 444 723. Relevant manufacturer designations:
- Beru 14 R-8 DV
- Bosch FR 8 LDC
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