I learned decades ago what the answer to this is, now I forget.

What busts up the rings? I used to think it was poor timing, but this thing was timed correctly. Lousy fuel? Overheat? Or just plain old age?

I need hints...

 

Probably the number one breaker of rings is detonation (pinging). Excessive/frequent overheating can weaken the rings, especially old high-mileage rings which can lead to breakage. Lousy fuel? Well yes...if it causes detonation. Poor timing can cause detonation, but you can still get it with the timing spot on in many cases, depending on load.

 

Thanks Dan, confirms my scenario. This is a high-mileage engine, and ran like junk, which led to the teardown. Ah, well, limber up the wallet, here we go again...