Head Bolt Torque Settings VAUXHALL Astra Mk VI (J) GTC (P10)

For the 2013 Opel Astra 1.4 Turbo, the cylinder head bolt torque settings, based on typical Vauxhall/Opel 1.4 turbo engines of that era, follow a common torque-to-yield procedure:

1. Initial tightening of the head bolts to about 35 Nm.
2. Then tighten further by 90 degrees.
3. Finally, tighten an additional 90 degrees.

This is a typical three-step tightening sequence used to properly torque the head bolts on this engine type.

The exact bolt torque in Nm is usually specified as:
- First pass: 35 Nm
- Followed by two successive angle tightenings each of 90 degrees.

This means the head bolts are torque-to-angle tightened, which is a common method for modern engines to ensure correct bolt stretch and clamping force.

If you want the exact tightening sequence for the head bolts on your Astra 1.4 Turbo, it often starts from the center bolts and moves outward in a spiral or specified pattern, which is important to avoid warping.

If you have access to the workshop manual specific to your engine code (GM A14NET from 2013), you will confirm this procedure. If not, this general procedure is widely used for Vauxhall/Opel 1.4 Turbo engines of similar years.

If you want, I can help try to find the exact tightening sequence diagram as well.

Summary:
- Head bolts initially tightened to 35 Nm.
- Then tighten 90 degrees.
- Then tighten another 90 degrees.
- Follow the tightening sequence pattern from center outward.

This is the common torque procedure for your 2013 Astra 1.4 Turbo head bolts.