It depends on the design of the machine. Some types have multiple cutters, others have a sliding collar on the main shaft that is repositioned for each bearing support. On a block such as a Chevy V-8, one cutter setting is used for all the bores. Since the stovebolt engine has four different bore sizes on the main bearings, The cutter either has to be reset, or more than one cutter holder must be used. The alignment of the shaft in the block determines the straightness of the holes, not cutter diameter.
Align boring is not an operation that is done often, even in a busy machine shop. The place I worked did an annual business volume of several million dollars a year, and specialized in heavy-duty Diesel engine work, in addition to a lot of automotive machining. We used the line bore machine four times in the 5 years I worked there. The procedure is part of block prep on every race engine I build, but it's extremely rare to need it on a normal rebuild.
Jerry
