With all the bearing clearances checked, I could install the crank for the final time so a healthy dose of assembly lube was applied on the bearings:
Then the crank was lowered into place and spun around a time or two to lube up the journals:
The lower case half was re-installed, along with the oil manifold plate, windage tray, main bearing bolts and perimeter bolts, then I began building up the pistons. The first step is to measure the gaps on the new piston rings. The best way to do this is to slip a ring into the cylinder and push it down an inch or two with an upside down piston like so:
Once the ring is in level, the piston is pulled out leaving the ring in the cylinder. The gap between the two ends of the ring can then be measured with a feeler gauge. You have to do this with all 32 rings (1 top ring, 1 middle ring, and two oil scraper rings per cylinder). Not all cylinders are exactly the same diameter, and not all rings are exactly the same size, so once measured, each ring must remain dedicated to that cylinder.
Next up is to install the rings onto the pistons. I bought new pistons that were over-sized by 0.25 mm to compensate for the over-boring of the cylinders earlier on. The oil scraper rings are first to go on and are easily installed with your fingers…
…but the two top compression rings are best installed using special ring expanding pliers:
With the rings installed, I then had to be certain that the rings weren't too thick for their grooves, so the clearances also had to be measured between the installed rings and their respective grooves in the pistons. Luckily all fell within specs and I was able to move on to assembling the pistons to their respective connecting rods. That was done by simply slipping the wrist pins into place and installing the little spring clip retainers:
Finally, here’s a shot of the completed rods and pistons ready to be installed in the block:
To do so, the rings must be well lubricated. I get an old margarine container, put an inch or two of oil in the bottom, and dip the whole piston top in it. It’s messy, but effective:
The connecting rod and piston is then guided down the cylinder and lined up with the crank. The expanded rings prevent the piston from sliding all the way in so they need to be compressed with a special band-style ring-compressor. I couldn’t take any pictures at this stage because it took too many hands, so here's a photo of me installing a piston in a different engine. Once the rings are compressed by the metal band, a wooden mallet is used to tap the piston down the bore: