Finishing up a propeller aircraft or tank

Would someone be so kind as to tell me how to create the finishing touches on say a B-17 0r B-25---specifically creating the black soot on the wing exhaust ports for the engines?Would this process be similar to creating soot on the cover over the engine of WWII armor?I'm just returning to modeling after many years away and would greatly appreciate any publications that are reccomended for beginning/understanding airbrushing and weathering/finishing of WWII aircraft and armor.I'm sure the technology has leaped way forward since I last did models in the early 70's.Many thanks.Rookiemarv.