Subaru 2002 Impreza Service Manual page 206

SPARK PLUG
2. Spark Plug
The spark plug's thread diameter is 14 mm (0.551 in) and the gap is controlled to a value between
1
.O
and 1 . I mm (0.039 and 0.043 in).
Gap: 1 .O
-
1
.I mm
(0.039 - 0.043 in)
NF0036
IG-4