Sorry in advance for what may be a silly question - but by major/minor walls are you differentiating between the walls between the cylinders and the walls that are on the sides of the intake/exhaust ports?
Cylinders 1,3,5 and 7 the major is the side of the cylinder wall closest to the lifter valley area and the minor is toward the outside of the block. Cylinders 2,4,6 ad 8 the major is toward the outside of the bock and minor is towards the lifter valley. Another place to sonic check is the front of cylinders 1,2 and the back of cylinders 7,8 I believe .180 is the min. there. Hope this helps.
