Ford 2003 Mustang Workshop Manual page 1559

21. Install the cylinder head gaskets.
22. NOTE: Install new cylinder head bolts.
NOTE: LH is shown, RH is similar.
NOTE: Lubricate the bolt heads and threads. Use clean engine oil.
Install the LH and RH cylinder heads and tighten the bolts in six stages, in the sequence shown.
Stage 1: Tighten to 40 Nm (30 lb-ft).
Stage 2: Tighten an additional 90 degrees.
Stage 3: Loosen the bolts a minimum of one full turn.
Stage 4: Tighten to 40 Nm (30 lb-ft).
Stage 5: Tighten an additional 90 degrees.
Stage 6: Tighten an additional 90 degrees.
23. CAUTION: Timing chain procedures must be followed exactly or damage to valves
and pistons will result.