Acetyline or Propane is more convenient, and much safer than starting fluid for spotting vacuum leaks. Just unscrew the head from a Propane torch, leave the metering orfice imn place, and attach a 2-foot length of 1/4" vacuum hose. It's much easier to pinpoint leaks, and there's no dangerous accumulation of flammable liquid like using carb cleaner or ether creates. If your shop equipment happens to include an oxy-acetyline torch, running a low volume of acetyline from the torch tip is another clean, reliable vacuum leak spotter.
Jerry