340 Pinging using 94

It's been asked, but not answered. What distributor are you running? I had a buddy with a stone stock '60 340 four speed Barracuda. It was pinging and he thought is was distributor (stock dual point). I had a fresh one on the shelf so we swapped them and the pinging went away. The only obvious thing I found when I took it apart was a vacuum advance plate that was froze up from dried grease. Fixed all that and it was still pinging. I had no way to measure it, but guessed that it was the point cam. Replaced it with one from another dual point and it fixed the problem. I didn't have a dwell meter to check it, but I suspect that was way off due to wear in the cam.