kb107

One thing that can occur to cause scuffing and forces a larger clearance is block distortion that can occur when all the bolts are put in a block and torqued. It will vary from block type to block type. I used to have to run an additional clearance in my Opel 1.9L builds because inserting the top 2 bell housing bolts and torquing them would distort the #4 cylinder out-of-round by at .003" + or -.

So without torque plates during boring and honing, the bores can go well out-of-round. IMHO, a reason to expect a gradual break-in sometimes; the rings may seal pretty well, but any high spots in bores will have to literally be worn down some.