Thanks everyone.

Dropping the assembled heads (cam towers, cams, etc) and cylinders to competition engineering later this week. He's going to inspect and instruct me on what all is needed, but when I asked about "honing" he said he does it all the time. Seems like changing out the rings without removing the pistons is no big deal with the proper tool. Thanks for the help everyone. Jumping back into my "build" thread here -> https://forums.pelicanparts.com/porsche-911-technical-forum/1108632-1978-finally-out-storage.html

Gotta clean the carbon from the ring grooves w/new rings, so pistons off for that. And don't hone the cylinders!

I did the same job a couple years back. Removing/reinstalling the pistons is no big deal. I did wrap plastic wrap around the block, and around the rods so the circlips couldn't wormhole their way deep inside the case. Good cheap insurance 👍

Soaking in diesel is an easy way to decarbon your pistons.

Kevin,

Your post above does not make sense. How could you change the rings without removing the piston/s from the cylinder/s? Were you referring from the connecting rod? Or this is another typo?

Tony

Yes i was referring removing them from the connecting rod

Each time I have failed to listen carefully to John, I have come to regret it.

I used an old, broken ring to clean the ring lands.

The carbon mostly just flaked off my pistons due to the moisture in the air, once they were out and sitting on the bench. I live in a humid place.

In for a penny…
Clean the pistons, if something goes wrong it needed to be fixed anyway!

Pistons are off and ready to be cleaned

For pistons, I found WD40 good for dissolving carbon buildup. I replaced my pistons but I cleaned a few to see what kind of damage the valves making contact with them did. Hopefully you marked each piston so it goes back in the original cylinder and kept the pins in their original order as well.

Scotchbrite pads with soap and water is what a few recommended for deglazing the cylinders. John W, Henry S, and Bruce P all recommended no honing, just deglaze. Again before you install the new rings, you should check ring gap which means putting the ring in the cylinder and using a feeler gauge to check the gap. I bought a cheap ring squaring tool on Amazon for the job. And when you go back together, make sure you oil the cylinders lightly before you install the pistons with new rings and have some assembly lube on hand to lube the rod and pin.

https://www.amazon.com/ProForm-67652-Piston-Ring-Squaring/dp/B003IN3ZEY

I ran my Alusil cylinders through John Walker's large industrial automatic parts washer. I suspect it washes parts with some sort of solvent. In any case, it changed the color of the insides of those cylinders from a dark grey to a light grey. I think it removed the carbon buildup between the silicon chips which are the actual business surface. Alusils are made using aluminum mixed with silicon, and then the aluminum is etched from the business surface as the last step in the manufacturing process, leaving the silicon poking out for the rings to ride on. I think the parts washer re-exposed those silicon chips.

Yes, light oil on the cylinders. Yes, assembly lube. Your newly assembled motor will make quite a few revolutions before those parts will be bathed in pressurized oil. Assembly lube on cams too!

Once again, I see no particular need to split the case but if this were my engine, I would at least wiggle the conrods just to see if one is looser than the others. If they all wiggle about the same (not much at all), then condition the heads and cylinders, reassemble and drive it like you stole it. Combustion chamber pressure presses the new rings against the cylinder walls. This improves the chances of the rings getting properly seated. Don't baby the engine in the first few minutes. Full throttle.

Honestly I think the rod bearings would have to be trashed to feel any wiggle.
When I had the heads rebuilt last fall, I put in new ARP rod bolts because John and others highly recommended it. I didn't split the case, I just took each one out, inspected the bearings for any wear signs, sprayed with Molykote and let dry, then reinstalled each bearing in its original orientation with assembly lube and tightened things down.

I replaced main and rod bearings, and all fasteners. But I did not recondition rods. When everything was half-assembled I noticed one rod bearing had more movement than the others. I did nothing about it. That was many years and miles ago. I even accidentally touched 7000 rpm a few months ago. Everything seems fine, but I will always regret not having the rods reconditioned.

If it blows up, I will see it as a signal from God to upgrade to a 3.6.

I've always been under the impression that some side to side wiggle is fine but it's the up & down motion where you don't want any play..

Rods will turn easily in the direction perpendicular to the line of the crankshaft, since that is their job. But rods should not wiggle much in the direction of the line of the crankshaft. And again, I am mostly just suggesting you wiggle them all, and see if they all wiggle about the same. "The same" being not much.

There is a proper lapping procedure using paste and felt pads developed by Sunnen for Alusil bores. Have had this done many times by a local machine shop with the correct knowledge and tools. 100% results to date.