Carb spacer query

I've just fitted a 1" carb spacer to my Holley 600v/s. Gone for a short run and pulled a couple of plugs to check for colour. the first one (cylinder 4) was light, light brown almost grey whilst the (cylinder 2) plug was more normal with dark brownish electrode. Haven't looked any further.

Should I be adjusting the air mixture or jetting having fitted the spacer?