What temperature should you put a 185 miller welder to weld a 7018 rod?

That depends on the diameter of your rod which depends on the thickness of the material you are welding. An e-7018 1/16" rod start at about 70 amps. A 3/32 rod start about 90 amps. A 1/8 rod start at about 110 amps. These are ball park ranges and you will need to adjust to suit. When the scale from your test beads chips off easily you are exactly where you need to be with the heat.