There are lot of things that can cause this. Make sure your coolant level is full, make sure the radiator cooling fan comes on when it's suppose to, make sure there are no leaks. On the bottom of the transmission front cover, directly underneath the lower radiator hose spout about three inches towards rear of engine is a weep hole, make sure it is not stopped up and see if any water or oil is seeping from it. The other things, bad thermoswitch, clogged oil lines or pumps, lean settings on carbs, sticking thermostat, clogged fins on radiator, corrosion in radiator, bad radiator cap, carbon build up in cylinders can all cause overheating. So check the easiest, less expensive things first.