Cylinder #7 down on compression

gtgto said
What should I clean up the top of the pistons with. is a wire brush on a drill to much? I would like to get some numbers off of hem. Why would someone put 8.5 to 1 pistons in a matching number block that came originally with 10.5 to 1's

Because people have been building engines with no compression for decades for no reason, other than the nattering naybobs said you couldn’t do it.

I’ve never 10.5:1 pistons with all those notches in them.