RE: Break-in a rebuilt engine?
The answer is....when you re-ring an engine, you de-glaze the cylinder wall.
This leaves fine scratches in the surface. These scratches rub against the ring.
A small amount of metal is removed from both surfaces the instant the engine
is started, and the first couple minutes of runnig. This is called the "mating" of
the ring.
If the surface is glazed, or too smooth, it will not break-in properly. You will
end up with lower compression, and lower performance from the engine. In
a wet sump engine you will have excessive oil consumption because the ring
never seated properly.
Even chromed cylinders are factory honed to finished size, and left with small
scratches in them. These types of engines generally use a soft cast iron ring
so the parts will mate. If a hard ring, or a chrome ring was used on a chromed
cylinder wall....it would never seat.
So the answer is....yes, the surfaced needs to be scratched up. The more
scratched up it is, the better and faster it will seal.