You haven't considered the tension of the rings, which may have been significantly lowered from a hot lean run. Also, and equally important is the ring gap. It should be .003 to .005". The blow by staining indicates to me that the rings definitely were not sealing well. I would add new Bowman rings for sure. What's 22 bucks to make your engine run better and last longer, especially since you have it apart now anyway?
Before re-assembly with new rings, I would take some Scotchbrite and acetone or carb cleaner spray and clean those pistons up. Lots of people like to use synthetic from the start nowadays, but I'm still an old fashioned fan of using dino oil for break in.... Why delay the all important break in by running synthetic oil and risking glazing the cylinders and never getting a good ring seal?
AV8TOR
Last edited by av8tor1977; 07-24-2014 at 08:33 PM.