Although Ford's 390 cubic inch eight-cylinder engine was first produced for the 1961 production year, it was not a popular engine choice until the mid-1960s. The 390 is perhaps most notable for being the first big-block engine installed in the Mustang in 1967, although it was replaced by the 428 engine in the middle of the following year. The 390's design varies slightly from most other engines of the time, such as the use of rocker arm shafts rather than pedestal-mounted rocker arms. For this reason, the 390's factory torque specifications should be followed.
Tighten each of the 390's spark plugs to between 15 and 20 ft-lb of torque.
Tighten all cylinder head bolts to between 80 and 90 ft-lb of torque.
Tighten all intake manifold bolts to within a range of 32 and 35 ft-lb of torque.
Tighten all exhaust manifold fasteners to within a range of 18 and 24 ft-lb of torque, unless the engine was installed in either the Fairlane, Comet, Mustang, Montego or Cougar, in which case tighten the fasteners to within a range of 15 and 20 ft-lb of torque.
Tighten each rocker arm shaft bracket bolt to between 40 and 45 ft-lb of torque.
Tighten all valve cover bolts to between four and seven ft-lb of torque.
Tighten the connecting rod cap nuts to between 40 and 45 ft-lb of torque.
Tighten the main bearing cap bolts to between 95 and 105 ft-lb of torque.
Tighten all flywheel bolts to between 75 and 85 ft-lb of torque.
Tighten the damper's bolt to within a range of 70 and 90 ft-lb of torque.
