if the headers are getting red up next to the motor then that's lean, if its got converters and its getting red down at the inlet of the conv, then the motor is either running rich and the gas is collecting at the inlet of the conv. or the conv. is 1/2 stopped up and causing a fire in the pipe at the conv. inlet. if you don have conv. then forget you ever saw this. set your timing and richen up your carb. a vac. leak will lean it out also. check your timing if its right leave it alone. up the primary jets a couple # and try it, untill you get it right. make sure you dont have a major vac. leak.