[77 TRASHCAN]

There's many different types of machines that you can bore an engine block with. Some are not as precise as others.
If you are boring a hole that is not completely round, everything else in the following machine work process is screwed also.

Maybe some of you that do this work on a daily basis can chime in on what you use.

The old timey method of using a boring bar (a machine that is clamped onto the block through an adjacent bore) is thought out dated by many. My machinist buddy doesn't like the looks of some of these newer fancy machines (knowing there are different types).

The clearances that piston manufacturers recommend are bore/hone jobs without the use of a torque plate, for their own liability reasons. I've seen 2 SBC's with 5 shiny spots in the bores, right by the head bolt holes...imagine that. Every brand of engine is different though.

I've read about Cliff and others tightening up the bore clearance on some engines. This cannot be done without a proper hone procedure using a torque plate! Other things have helped in this area, include better light weight pistons, better machine techniques (including the folks using the machines, above all!) better hones and better torque plates.

I've seen my engine builder in his shop measuring the bore of a block with a dial bore gauge, many times...back then I wondered why...