Honda Civic Wagon 4WD 1990 Owner's Manual page 83

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Spark Plugs (cont'd)
Spark Plug Replacement
Replace plugs one at a time, so you don't get the wires mixed up.
1. Clean any dirt from around the spark plug base.
2. Disconnect the spark plug cap, then remove and discard the old
plug.
3. Check the gap of the new spark plugs before installation.
Plug gap should be: 1.1 mm ( 0.04in ) .
4. Thread the new spark plug in by hand to prevent cross-threading.
5. After the plug seats against the cylinder head, tighten 1/2 turn
with a spark plug wrench to compress the washer.
6. Reinstall the spark plug cap.
CAUTION:
The spark plugs must be securely tightened, but not overtightened.
A plug that's too loose can get very hot and possibly damage the
engine; one that's too tight could damage the threads in the
cylinder head.
PLUG CAP