Spark Plugs ISO Metric Threads
Reference data and engineering information about spark plugs iso metric threads for piping systems applications.
Overview
Engineering reference data for Spark Plugs ISO Metric Threads in piping systems.
Key Formulas
Continuity
Mass conservation in pipe flow.
Pressure Drop
Darcy-Weisbach equation.
Pipe Area
Cross-sectional area of a pipe.
Variables
| Symbol | Description | Unit |
|---|---|---|
| Pipe diameter | m | |
| Flow velocity | m/s | |
| Pressure drop | Pa | |
| Friction factor | — |
Data Table: Spark Plug ISO Metric Thread Dimensions
Size | Major Diameter(mm) | Minor Diameter Range(mm) | Pitch(mm) | Tap Drill Diameter(mm) | Thread Depth(mm) |
|---|---|---|---|---|---|
| M10 x 1.0 | 10.0 | 9.153 - 8.917 | 1.00 | 9.20 | 65 |
| M12 x 1.25 | 12.0 | 10.912 - 10.647 | 1.25 | 10.9 | 72 |
| M14 x 1.25 | 14.0 | 12.912 - 12.647 | 1.25 | 12.90 | 72 |
| M18 x 1.5 | 18.0 | 16.676 - 16.376 | 1.50 | 16.75 | 68 |
Source: ISO 28741
Related Standards
The thread dimensions and tolerances for spark plugs and their cylinder head housings are specified within a family of interconnected ISO standards. Compliance ensures interchangeability and correct fitment.
- *ISO 28741: Road vehicles — Spark-plugs and their cylinder head housings — Basic characteristics and dimensions.
- *ISO 68-1: ISO general-purpose metric screw threads — Basic profile.
- *ISO 261: ISO general-purpose metric screw threads — Selected sizes.
- *ISO 965-1: ISO general-purpose metric screw threads — Tolerances — Part 1: Principles and basic data.
- *ISO 965-3: ISO general-purpose metric screw threads — Tolerances — Part 3: Deviations for constructional threads.
Minor Diameter Tolerance & Thread Angle
The minor diameter of the internal (female) thread in the cylinder head is specified with a 6H tolerance class. The threads for both the spark plug and the housing use a standard thread angle of . This ensures proper engagement, sealing, and mechanical strength under combustion chamber pressures and temperatures.