Eight pistons and a postal scale. First weigh in and wouldn’t you know it, one light one and the rest pretty close, but all heavier.
Sorry for the blurry photos. they look OK on the screen but…
All the pistons have some aluminum oxidation from many years of poor storage. I wet sanded each piston with 600 grit only to the point of removing any thickness. I didn’t worry about the stains left in the metal.
Here’s the tool I used to remove metal from each of the heavier pistons. Adjustable speed so I could set it to remove metal slowly.
I removed casting metal from the thick flanges at the bottom of the piston. I tried to take roughly the same amount from each side.
The one on the right was a heavier piston and this is how much I had to remove to get 4 grams off the weight. Looks like maybe a quarter to a third of the thickness.
Now back to the parts washer to remove all the filings. Then I’ll gently heat the each piston and get the stuck pins out for cleaning and oiling.