This maybe a stupid question but I could use some clarification of exactly what the ridge is? My cylinders look pretty much like the picture below and I feel a ridge at the bottom of the dark area. But the deburring tool recommded by someone at Auto Value will only operate around the top of the cylinder. I had rented a ridge reamer from Partsource but the damm thing appeared to be broken as it's cutting head wouldn't slide against the cylinder wall even though I followed the instructions. When I mentioned that to the behind the desk he didn't even open the case, just said he never used one and that was that. Am I supposed to remove the top, the bottom or is that whole dark area considered the ridge?
That ridge is were the rings stop at top dead center. You need to remove the entire ridge before putting the engine back together.
If you can "click" a finger nail on the ridge then you need to bore the block, for every .001 you gain in bore you add PI (3.141) to your ring end gap, so if you have .010 wear in the block you'll add .031 to your ring end gap.
DO not ever use a ridge reamer in a block, I have seen more blocks that would have bored .030 go to junk becuse of a ridge reamer...