The rings are lubricated.
The piston is now slid into a ring compressor. The best type of ring compressor is a cylinder with a tapered bore which progressively compresses the rings as the piston is pushed into it.
The piston and and rings are now pushed into each bore. The piston is gently tapped into the bore with a mallet handle. Care is taken here as to not pinch and break the rings on the block’s deck surface.
The piston is now in the bore!
The piston is carefully pushed down until the rod is sitting on the crank. Great care is taken not to scratch the crank journal.
The rod caps are bolted down.