You MUST consult your vehicle's repair manual or a reputable online resource specific to your 1998 Cavalier's AC compressor model. The manual will provide the exact air gap specification in millimeters or inches. Trying to guess or use a generic value could damage the compressor.
Attempting this repair without the proper information and experience could result in further damage to your AC system. If you are not comfortable with this repair, it is strongly recommended that you take your vehicle to a qualified AC mechanic.