Jerry, this "ping" I discovered while revving the engine when trying to find out if my generator was charging right. It sounds like glass bottles rattling together. I was not moving the truck at all when I discovered it. And while doing a search, I found multiple times posts that recommended retarding the timing because today's gas is better than 50 years ago. But now, this "ping" is not the problem, it's the small backfire sounds coming from the carb, as explained above.
