heli-coil

Just got my used alun intake for the Dart and found that one bolt for the themostat is strip I can tighten it up but the bolt goes down far and only about 4 threads holding it tight,is that ok.the intake is off should I take it to a machine shop to have them install a heli-coil.or can I do that when the intake is on the motor,o ya I have never installed a heli-coil befor any tips thanks.PS GO Tony Go.