Tuner wrote:
If the cylinder wall is finished smooth enough with 400 or 500 girt stones for the final honing and a little extra love is invested in some polishing there is no breaking in of the rings or walls to do. Moly rings are lapped to a light-tight finish in manufacture and do not require a rough wall for “break in” – “break out” is more like it when the walls are rough.
http://www.federal-mogul.com/en/Afterma ... ly-Chrome/
I learned the following tricks from a TRW field rep that came to the speed shop where I worked in 1966 to school the old-time machinist who was finishing walls too rough for the new (at that time) moly rings. I’ve seen many and done every engine that was mine to influence with this procedure ever since and never, ever, had any problem with ring seal or oil control. I’ve had plenty problems with people who wanted to argue about it.
If an old penny (actual copper-not copper plated zinc- pre`79-`80?) can be rubbed on the cylinder wall without removing any copper, it’s smooth enough to be relatively safe but not necessarily smooth as would be ideal. It is my opinion that as smooth as possible isn’t smooth enough.
With a spring loaded three-legged trapezoid type “glaze breaker” hone put duct tape sticky side out over the stones (do a good job of securing the tape behind the stones) and use 400 wet-or-dry paper to polish the cylinders. Put the paper in the cylinder first and let the hone expand into it so the paper sticks to the duct tape. If the cylinder is large, a sheet of paper may have to be cut in half and the haves offset to get full coverage on all three stones. The two pieces have to be overlapped the right direction so they don’t act like a sprag. One way they trail and turn easily and the other they wedge up and jam. Use a ¼ or 3/8 drill motor and trickle water from a hose while you polish. WD 40 is OK but it’s messier and you have to wash with water in the end anyway. A trickle of water flushes the trash away and the paper doesn’t load up as quick. Stroke up and down to generally follow the existing cross-hatch scratches. If you have the patience for it, follow the 400 with 600 and 1000 paper. Naturally, you have to be careful not to tear the paper or let the stones touch the wall and scratch it. I don’t think the walls can be made smooth enough.
400 paper will polish the walls and achieve the “plateau finish” that has been the subject of a lot of mumble over the years and won’t remove enough material to eliminate the crosshatch marks of the stone hone job so there will still be enough oil to keep the “don’t make it too smooth” crowd happy. The surface of the moly ring is full of microscopic fractures that are where the oil molecules hang out, so the wall doesn’t have to be rough.
In the early 70’s when GM released the “Power Manual” with instructions for race engine preparation the advice was to finish with 400 or 500 grit stones for moly rings.
The real clue was in the advice against honing or “glaze breaking” when re-ringing an un-damaged cylinder.
I say again, GM advised to not touch a smooth broken-in cylinder wall at all when installing a fresh set of moly rings.
The reduction in friction with smooth walls realizes a significant power increase. In one of the books it was in Italics, they were trying to get the point across, but old urban lore dies hard.
Folks who have studied piston and ring friction in laboratory circumstances following scientific method have found the smoothest finish has the least friction. Imagine that? A postulate is the least friction available is found when the surfaces are smoothest (this applies to bearing journals too) because of Coulomb forces. At the atomic level the surface of all matter is an electron cloud. Electrons repel each other because they have the same – charge, sort of like a maglev train but on the atomic level. A smooth surface has the most uniform electron cloud.
I suppose with chrome rings the walls and rings have to grind each other to fit so I guess a rough finish is necessary. I don’t know. I don’t use chrome rings. I have someone whose opinion I trust, he handles it and I don’t worry about it but for moly I think there’s no such thing as too smooth.
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