US shops work in ft-lb; metric shops work in Nm; small fasteners spec in in-lb; some European specs use kgf·m. Get the unit wrong and you either over-torque (snap the bolt) or under-torque (leak / fail).
The conversions
- 1 ft-lb = 1.3558 Nm (or simpler: × 1.36 for shop math)
- 1 Nm = 0.7376 ft-lb (or simpler: × 0.74)
- 1 ft-lb = 12 in-lb (exact)
- 1 kgf·m = 9.807 Nm = 7.233 ft-lb
Common engine torque ranges
- Spark plug: 15–25 ft-lb · 20–34 Nm
- Valve cover: 7–10 ft-lb · 9–14 Nm (often spec'd in in-lb: 84–120 in-lb)
- Intake manifold: 12–25 ft-lb · 16–34 Nm
- Rod cap: 35–65 ft-lb · 47–88 Nm (then angle-torqued)
- Head bolt (TTY): 22 ft-lb + 90° + 90° (typical LS-style sequence)
- Main cap: 65–110 ft-lb · 88–149 Nm