Honda Accord Sedan 1999 Owner's Manual page 227

Spark Plugs (4-cylinder Models)
4. Put the new spark plug into the
socket; then screw it into the hole.
Screw it in by hand so you do not
crossthread it.
Maintenance
5. Torque the spark plug. (If you do
not have a torque wrench, tighten
the spark plug two-thirds of a turn
after it contacts the cylinder head.)
Tightening torque:
13 lbf . ft (18 N . m,1 . 8 kgf.m)
NOTICE
Tighten the spark plugs carefully. A
spark plug that is too loose can
overheat and damage the engine.
Overtightening can cause damage to
the threads in the cylinder head.
6. Install the spark plug cap.
7. Repeat this procedure for the
other three spark plugs.
Specifications:
NGK: ZFR5F-11
DENSO: KJ16CR-L11
Spark Plug Gap:
0.04 in (1.1 mm)