Generally the clutch plate bolt is torqued around 115 inch pounds on most compressors. Honestly Ive done so many I just do it by feel anymore since it is not a considerable amount. Using a 3/8 drive ratchet with a moderate tug will surely be sufficient. More importantly making sure the gap between the clutch plate and pulley bearing is between .035mm to .60mm. You don't want to big of a gap or the compressor may not engage or too little may not allow it to disengage once the engine is at full operating temperature.