Electrical Problem?

hi, having similar probs, what ideal voltage should i have on coil +? its running through a ballast ,when you rev it does go up to 12v,normally sits at 6v...have mopar orange box / no points and accel coil,car does cut out after 20 mins,guessing somthing getting hot! ps, what ohm should ballast read please? have spare,thankyou, nathan.