[PeterH-79MH]

Curtis,
the pinging you describe is bad for the motor.
Causes for pinging are:
low octane fuel (use at least mid grade)
timing too advanced
bad timing chain
I found the best timing on Motorhomes is to set it a few degrees before pinging under load, which in some cases may not correspond to manufacturers recommendations.
My previous Class C Motorhome had a GM 400 engine.
When I checked the timing it was set to 12 BTDC. I freaked out and set it to 6BTDC per label on the air cleaner. It ran ok down here in Texas, until I drove it to the mountains of New Mexico and Colorado. I couldn't even get up any of the smaller grades. All stressed out, I finally advanced the timing to just before pinging and was able to go over Wolf creek pass with no problems.
I assumed the mileage and age of the old 400 was the reason for having to run so advanced.
A year later I replaced the 400 with a 350 crate motor from GM. Lo and behold, the only way it would run properly was around 12 BTDC.
Since i doubted myself, I took it to a very knowledgable mechanic friend of mine, who said, you can not run that new motor that advanced.
After he was done, he had it back to 12 BTDC.
If you check your timing and you find it to be running advanced, back off only a bit to get out of the pinging zone.