[brucepick]

Welcome to Ecomodder and to the thrifty Honda owner's bunch!!

My '97 HX came with the original owner's manual - which specifies:
NGK plugs - ZFR4F-11.
Other Civics of the same vintage used a different heat range version of the same basic plug. I'd go with the ZFR4F-11 per Honda's spec.

My local Honda dealer usually doesn't have them. Some independent parts stores will have them, because other brands also used that plug.

Honda also specifies a pretty low torque tightening spec. 2/3 of a turn if working without a torque wrench, and only 13 pound feet with a torque wrench. I go one pound higher than Honda says and turn them to 14 pound feet.

The manufacturer's notes on spark plug box give a higher torque spec, about 18 lb-ft. My guess is that Honda knows the strength of their head casting and they don't want you going all the way to 18 lb. Stripped threads in head = NOT FUN. Probably would require a new head due to lack of space to add things like a healacoil.