how can i set the fireing other of chevrolet truck v6engine
You can't set the firing order, its preset. If you are asking about adjust a distributor then take out the first spark plug. Put your finger in it and turn the engine from the front until you feel the wind. You can also put something long and hard plastic like a hanger cut to see how hight it goes. If the engine is hard to turn remove more spark plugs. What you want is piston #1 to be at the highest level that it can be. Then position your distributor to #1. It that is not obviously marked and auto parts can print you out a diagram.