Re: New rings and bearings on a used engine.
Rebuild starts with a compression check. If it passes compression check bring engine up on TDC mark on damper, then mark distributor to manifold and note position of rotor (digital camera remembers all). Pull the distributor out of engine; the pull intake manifold and carb as a unit. Pull the heads after removing exhaust manifolds.
Now that your wife is ready to kill you and you have antifreeze running down the driveway; take a moment to examine the cylinder walls. After noting If there isn't a taper to the bore or a ring ridge at the top of the bore (and that it appears shiny and uniform top to bottom, no lip) you could consider fitting a set of std. rings back on and not notice a lose of cylinder seal. Take another photo or two, not only for posterity, but to remember which piston was were at the TDC mark on the damper.
If your shade tree comes with a lift now is the time to raise the car. Failing in that we are going to drop the oil pan (you just thought you were all grimmmy). We (hopefully you have enlisted some help for this project) do this to get to the rotating assembly (crank rods and pistons).
Bearings are just as easy to get to as everything else has been up to now. Once to pan is off and the oil stops dripping down on you, get your camera again. This is were it gets technical. Focus on the rods, take an in focus rod/crank picture (turn the flash on).
Pull off both rod nuts on whatever rod is half way between being to far up in the block to get to, and being at the bottom of the stroke. Rethread a nut onto the block side rod bolt. Gently tap the rod bolt nut (with a small hammer) being careful not to knock the bolt out of the rod. This will separate the cap off the rod. Rotate crank away from rod so that you have room to remove piston and rod assembly out the top of the block. Look at the rod journal. Is it shinny and polished (don't wipe the oil off, just look). Look at the rod cap. Is the bearing shell still in the cap? Good take a picture to remind you which way the shell fits in the cap. See that little notch, the bearing goes back just that way.
Now you can wipe off the oil on the rod cap only. Is there a number stamped on it? (1-8 would be nice for an eight cylinder engine). Number there, no problem, look at the bearing. Is it a uniform grey color? Yes is good here. Is it brass colored? With scratches? (if yes time to look for a crate engine).
If the cap is numbered put it aside and find a long thin blunt (no points) punch/rod/garden tool anything that will fit between the crank and the side of the engine. Beat on the end of this improvised tool until your assistant who hasn't gotten dirty yet tells you the rings are out of the block (there are three of them, two thin one thick). Have assistant pull piston rod and hand it back to you. Put the numbered cap back on rod and set aside (no number; have assistant mark with felt tip pen, blood what ever is handy so you know were it goes after we install the new rings.
Repeat process seven more times. To re-ring the pistons we will need to first clean them. Mechanics use brake cleaner 'til their head hurts (in another life they would have painted cars but the EPA took the fumes away). Remove the old rings with some patients and a small screw driver. From the top pop out one end of the ring and pull it above the top of the piston. Working around the piston keep pulling it out and up. See how easy this is? Imagine us reversing this procedure while worrying about breaking the fragile cast iron rings.
Next groove we have to pull out further and up further. Break one yet? Sharp aren't they. No; you are doing well, and there is a future for you in the automotive trade provided your not allergic to brake cleaner.
Last groove, This is easy if you follow the correct order. There are three separate pieces here, not one. Grab the top rail. Same drill; out and up. Notice how easy this is. This is because these are steel rings not cast iron, and are much more spring like. Now the bottom rail, out and up. Now look for a gap in the separator. See it, pry it apart if stuck and it will practically fall of. More cleaning, just chemicals in the ring groves. You can wire brush the tops of the pistons but if they are old enough to have seen leaded gas I wouldn't.
One thing left, the crank. Unbolt the cap screws and remove the caps one at a time. Same examination procedure, shinny crank, grey bearing babbit. If we find any thing different all bets are off back to the crate engine. Remove the bearing shell from the cap, clean it. With a clean cap we replace the old bearing shell with a new one.
Now it gets interesting. We need our small hammer again and our small screw driver. We want control not brute force. W will tap on the babbit bearing at the block crank saddle. If we do this right the bearing will rotate around the crank to fall out. And it will if we choose to beat on the side that doesn't have the bearing tang and notch (but we thought of that already right). WD-40 time, lube bearing, crank, fingers everything but eyeballs as we insert a replacement bearing back in again (it helps to loosen all the caps a bit (1/8th inch) and let the crank lie in the lower caps). Clean cap we laid aside goes back on now. Repeat process four more times.
Brings up the rear main cap with the oil pump and the distributor to oil pump drive shaft and that very fragile oxidized white nylon joint holding the two together. We also have an oil seal to add to the mix (and the thrust bearings are not going to go gently into the night as Wily once said). Just have to be more cautious. Drop the cap, and remove all straight down. Lay gently aside, in hope the drive shaft stays attached. Same procedure as before; we just are playing with a more determined foe this time as the bearings and seal will want to stay put. Done? Clean cap with more brake cleaner. After the block side the cap should be a piece of cake. Once all bearings and seals are in place, run the main caps back up a little at a time until everything is snuggled up a 1/8th turn past finger tight. Torque them to specs.
Now we reverse the whole procedure with the piston rings. We have to space the rings so the gaps are 180° apart on the oil ring (the big wide one on the bottom) and the two top rings are gaped 120° apart from the oil ring (look it up in a geometry book). Once all the rings are on; we get our Ring compression tool and insert the piston number one into the cylinder hole number one. Crank throw rotated to the bottom of the stroke (furthest away) and the piston top up, with piston facing the front of the engine (for this part you will need a Chilton's, but basically all pistons are marked with a notch, and arrow, something to distinguish pin offset).
Tap said piston gently into the hole until the top is flush with the block. If your assistant has been tapping the piston in you need to get under the car and guide by hand the rod almost to the journal. Insert the rod bearings (you've had lots of practice by now) bearing flush and retained by it's tang beat it onto the crank. Install cap bearing. Remember our picture of the bottom end make sure your cap looks just like it when placed back on the rod bolts. Oil threads and torque rod cap bolts. Repeat for effect seven more times. Bring engine back up on TDC mark. Look the same as the picture? Great, if not rotate it around to TDC again (didn't know there were two of them did 'ya?)
Get a brew, and then clean all gaskets. Better yet have your assistant clean all the gaskets, you’re the mechanic here. Reverse disassembly procedure with appropriate gaskets. Torque as needed to taste. Refer back to our first set of pictures. Turn distributor rotor to same direction as it was when it came out. Insert the distributor and turn shaft 'til it matches the marks you made. Reconnect all lines and battery cables and start it up. Time the engine and you have just done a back yard referb. With practice comes speed; though it just may be the effects of the brake cleaner. Stop sniffing that stuff!