How to read a Magneti Marelli spark plug reference
A Magneti Marelli short code encodes the range, the electrode type, the thread & hex size, the heat grade and the gap. Here is how to decode it.
A Marelli code such as SNB7001-9 reads: S (range) · N/I/P (type) · A/B/D/E (thread × hex) · heat grade · progressive number · -gap.
1. Type of electrode
- N — nickel
- I — iridium
- P — platinum
2. Thread size × hexagon
| Letter | Thread | Hex |
|---|---|---|
| A | 14 mm | 20.8 mm |
| B | 14 mm | 16 mm |
| D | 12 mm | 16 mm |
| E | 12 mm | 14 mm |
3. Heat grade
The heat grade tells how well the plug sheds heat: low numbers = hot (low-power engines), high numbers = cold (high-power engines). Marelli grade vs others (approx.): Marelli 2 ≈ NGK 2 / Bosch 10 / Denso 9; Marelli 6 ≈ NGK 6 / Bosch 7 / Denso 20; Marelli 10 ≈ NGK 10 / Bosch 2 / Denso 31.
4. Progressive number
A sequential number identifying the specific type within the range.
5. Gap
The number after the dash is the pre-set gap in tenths of a millimetre (-9 = 0.9 mm, -11 = 1.1 mm).
6. Tightening torque
Torque depends on the seat, thread diameter and cylinder-head material. Flat seat (with gasket): 12 mm 15–25 N·m (iron) / 15–20 (alu), 14 mm 25–35 / 25–30. Always follow the value printed on the box.