Yeah, step one, clean everything. Start with the work area.
Step two, repeat step one...
When you get to step twenty-three or so, and get to start putting stuff together,..
Go get an engine bag. They're occasionally made of black plastic and used inside garbage cans. Unless you have large clear bags around... You want to be able to keep this thing slightly cleaner than a hospital operating room if you take a break during assembly.
Look everything over. Every oil hole in the crank (flashlight helps) and block. Shoot 'em with solvent or carb cleaner. I know your machinist cleaned it. So what. Even when I was the guy who washed the block/crank/etc. I still checked one last time B4 assy. Ten minutes WELL spent.
Bag all the parts you've cleaned (crank, rods, pistons, etc.).
I use paper towels and WD-40 to check the bores for any grit/dust left from honing, handling or storange. Then chase any lint from the paper out with a VERY clean hand and more WD. Check the cam bores for contaminant with a finger and WD.
Once that's done, I'd grab the rings, and check them ALL for correct gap. One-by-one. Yes, it's tedious. But a butted gap will RUIN your day.
I personally believe in buying gap-to-fit rings. But even if you get the ones with the 'big enough' gaps, check 'em.
If you're putting in your own cam bearings, do it now.
If there is a cam plug (like a freeze plug) at the back of the block, it's time to install. Smear the outside with a SMALL amount of sealant on the corner between the flat of the plug and the diameter of the edge, so that it will drive in and have a tiny little bead of sealant when you get it put in.
Now, put in ALL oil passage plugs. And ALL water passage plugs. If you have the sending units, you can put 'em in now, too. I like teflon tape on tapered threads. Some guys like teflon goop, other guys like other stuff. Personal preference.
Drive in all the freeze plugs. I like a little bit of GOOD quality silicone smeared in the bore when they go in. If there's a pit or imperfection, it can bail ya' out.
Now, take a coffee break, then check for ANY holes left open. Is everything plugged that should be? I'm a believer in getting them ALL done at once if possible.
Next step, grab the cam (which you've already cleaned, right?), put some lube (motor honey is good) on the journals and get the longest bolt you can screwed in the front of it.
If you're able to stand the block on its butt so you can drop the cam straight down, that's best. But if you can't, then get the block oriented so you can get one hand under the cam inside the block to guide it as you put it in. You DON'T want to gow up the journals, or you're going to go backwards. DAMHIK!
Cam is in and spins free, right? Great! If not, find out why. It won't 'faith heal'.
If the engine has a cam retainer plate, put it on at this time. Red loctite on the mounting hardware.
Now it's time to put the crank in. Well, actually the main bearings; the crank comes along a bit later...
Before putting the inserts in, run a CLEAN finger over all the journals in the block, and along the sides where the thrust bearing will go. Last chance to find any dirt, chips, or burrs before they cause grief.
When putting the inserts in, I rub a CLEAN finger over the back side to make sure that there's NO lint/dust/debris on the back. If that gets caught between the bearing shell and the block, it's going to close up your oil clearance at that spot. Not good.
Everything good? Okay. Then I put the insert in carefully. There's a kind of a feel to how it should pop in that's hard to break down into words... but I'll just keep typing.
If you feel any 'grit', or 'grind' as it goes in, pull the insert back out and look
real close for a little curl of metal cut off of somewhere, or a tiny chunk of grit. You can feel a miniscule amount of dirt if it's in there (think less than a hair in size) - which is still too big! Anything other than a clean 'snap' of the insert into the saddle is unacceptable, and calls for disassembly and inspection.
I like to put the inserts in so that the end with the tab sticks up about an eighth of an inch or so, and slide 'em into position. Personal preference, I suppose, but I can feel if there's a little chunk of crud in there as it slides that last little bit.
Once all the main inserts are in the block, it's time to put the crank in. You did clean it already, and left it in a bag after cleaning, right? Well, pull it out, lube the journals and thrust surfaces with some motor honey, and set it in. Carefully - don't drop it.
Now, get the one main cap with the thrust bearing, and install just that one, torqued to spec.
Take a prybar, or tap the crank with a soft face hammer to drive it to one end. Put a dial indicator on the block, and pry the crank the other way. Measure the travel, and compare to your manual.
If that's good, then you can install the rest of the caps with main bearings, torque 'em all down, and check that it turns easy.
If you're building a Honda, or other new engine w/ a one piece rear seal, pop it in now. Otherwise... pull all the main caps back off. Now, I hear you cussing at me for having you go backwards. There's a reason: if you have any funny feel, you won't catch it with the main seal in. C'mon it's ten minutes' work, and you're good at tightening those bolts now; lots of practice.
So, pull the crank out, put in the main seal, drop the crank back in. At this point, I like to use a little anaerobic sealant between the rear main cap and the block. Just a tiny bit; you don't want it squishing out onto the bearing journal or something.
Put the main caps back on and torque the bolts, I promise not to ask you to take 'em back off.
Anyway, the cam is in; the crank is in. Soon, we'll put the timing set in, and then hang the rods.
But that's another day's typing.
-Bill