About 7 or 8 years ago I went on a 200 mile highway trip with my 69 Hemi GTX. As I was driving it became harder and harder to go up hills without it pinging. I finally made it to my destination and after checking it over, sure enough the timing had advanced to almost 50 degrees total. I got close to 20 MPG on that trip. Huge advance and having to featherfoot it on the hills does have it's advantages.
