How many of us are there? Owners of Dodge based RV's?

We set ours to 15° BTDC, but it pinged a bit too much, so we set it back to 8° BTDC, where it runs fine (the spec on the 440 is 7½° BTDC).

So try 15° and see how it does. If it pings, then back off a little at a time until it stops pinging.