I scraped out the ring grooves and I did get a lot of carbon out but it didn't seem to do anything. I installed the piston nearest the back of the block and that went in as easily as before... I had to beat it in with a mallet. With that piston installed and torqued to spec, I could still rotate the crank shaft with much difficulty. When I installed another piston, I couldn't move the crank at all.

Is this even remotely normal? I still need to be able rotate the crank to install the rest of the pistons.