Popping in exhaust

Many years ago when I was still very green...I installed an accell distributor and supercoil....and all I got was popping from the exhaust...the more I revved the more it popped...come to find out between the coil and distributor needed a ballast resistor...voila it quit popping and drove great...everyone was telling me burnt or bent valve on an engine with less than 1000 miles....it was electrical....hope this helps a little