J D, The ridge was left from the previous rings 'stopping point'. Now with new rings & crank bearings the new rings will be right at the edge of the ridge at TDC, almost guaranteed bumping into it. Keep in mind the new bearings, having closer clearances, will 'raise' the crank higher, ever so slightly. The old ring top ring edge wore down a small amount, along with the cylinder wear. You install new rings, they are unworn & so the top edge is just a couple thousandths 'higher'. Then, with heat, you get rod elongation. Thats why the ridge should ALWAYS be removed. Normally the bores are honed, at least with a 'glaze breaker' to provide a proper surface finish to seal & seat the new rings. This in itself requires cutting the ridge. If not done, at the very least you can destroy the sealing edge of the new rings, & possibly crack a piston groove land. Doug
