In an ideal world we would all have high-output, hot-rated alternators. With a single
belt you really can't put more than about a 100-amp alternator on there without belt slippage anyway, which can really heat up the alternator. So keep the belt tight, and get some really good quality belts (like Gates or Napa green ones) which will make a big difference. The fan will also help a lot with temperature, in my experience. Many alternators, believe it or not, are designed to suck air in at the back (where the cables
attach) and push hot air out at the front. Make sure your fan moves the air in the direction it is supposed to go.