I've got a Chevrolet small block 350 here at the shop that is bored thirty thousands over and only has a few 1000 miles on it. Whoever put the motor together lined up all the ring gaps for the most part.And it burned oil. Along with Not installing any valve seals on the valves. I'm getting the seals installed on the heads and I'm going to put some new rings in it. And I want a recommendation on what size and grit ball home to get to finish the cylinders. I found a couple with 250 grit and 4 in an eighth diameter. I was thinking that one
Interesting on the ring gaps, I’d always thought the rings did some rotating in the bores. I agree though not proper practice. That said, I asked the same question a few years back here, pretty sure I was told 300 grit hone, couldn’t find one locally so used a 400 instead. But it is 4.125 in diameter.
If there is proper cylinder finish, the rings will rotate as the engine runs. In other words they likely would not have remained lined up for long. That said, if all 8 were lined up, the cylinder finish may be problematic. The oil burning was likely 90% or more due to the missing valve seals. Ultimately, the ring manufacturer will have a spec range for the cylinder finish, and that should drive your choice in honing equipment.
I've had luck with whatever the machine shop supplies me for stock rebuilds. I believe they are cast iron rings but could be wrong as the machine shop has closed.
When I was young, way back in the middle of the last century, we/I used wet or dry paper, the almost black stuff, wrapped around my fist to " bust the glaze" when installing rings. Never had a failure. Ben
Exactly In another life, I was a Small V8 Engine Development Engineer at FoMoCo. We built and ran several engines with precisely spaced ring gaps and ran them on the dyno. In all cases when the engines were disassembled and inspected the gaps had moverd around the ring grooves in seemingly random order. [The oil ring rails stayed in the same spacing with the oil ring expander as when assembled though.] On other assignments, I took an engine that was averaging ~2500 miles/quart of oil on a specific dyno test cycle and removed the valve stem seals and repeated the test cycle. The oil consumption rose from 2500 to 400 miles/quart.
And over in Ann Arbor, we had interesting HC results with those 5 liter engines. Those heavy hydrocarbons really messed up fids. We went to using heated fids from the diesel cells.
If the crosshatch on the cylinders isn't proper, no matter what you do, it may be a mess. Cast iron rings are the softest and seat the easiest. They also have the shortest life. If everything is questionable, I would use cast rings but don't hit the cylinders more than about two strokes with a berry hone if the crosshatch is clear and visible. You don't want to destroy the crosshatch because that's where the oil that provides piston seal is stored. It would be good for you to watch some of Total Seal piston rings videos on the subject. Good luck.
I think ring manufacturers have a spec for grit and clocking the ring gaps, I have always followed them. Not sure if ring rotate when running, but if they do at the same rate the clocking would stay about the same.
Just a bit of trivia, but when I use a bottle brush hone, I use a reverse able drill and hone one cylinder running the drill forward and the next one oin reverse. It helps ,keep the proper shape on the stones.
Just about any sanding product can be stapled to a dowel and spun in a drill. It works great when it works but sometimes requires a lot of fiddling depending on what you're doing and the results you're looking for. I've never done a cylinder this way though.
My understanding of moly or chrome rings is that the cylinder must be finished correctly with a proper cross hatch and with dimensions on spec. My understanding on CI rings is that they are more forgiving on finish and dimensions. I could be wrong but that is what I was taught. Dan
The angle of the cross hatching is also important. Too flat rings don't rotate, too steep they don't hold oil.
Moly rings are a good choice. They are actually made of cast iron with a moly coating infused or plasma sprayed on the wear surface. Additionally (from the interweb): Moly rings are made of a plasma-moly inlay that contains chromium, molybdenum, and nickel. The plasma-moly inlay process involves spraying an alloyed powder into a channel in the ring's face to create a hard, porous, and wear-resistant surface. Moly rings are a good choice because of their scuff resistance and ability to retain oil. The porous nature of moly allows it to retain oil in the face of the ring.
Be sure the second compression ring is installed right side up , each manufacturer seems to have a different way of identifying which side is up & which side is down . Finding accurate manufacturer info is sometimes difficult . Mahle moly rings have a good track record , IME
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