Machining a Piston from a Casting

[hermetic]

Looking at the above picture, it strikes me that as long as the gudgeon pin hole is perpendicular to the bore and the con rod bush, a little axial displacement in the bore is immaterial. Of course if it is NOT perpendicular, then it won't work!! I assume this is not a two stroke, and axial position of piston in cylinder is not critical to port positions and ring pegs? I have none to check on, but I am sure I have seen this defect on mass produced replacement pistons! the lack of a core in the casting, which would give a position on the outside of the piston leaves you relying on the concentricity and uniformity of the gudgeon pin bosses inside the piston as a centering point, and at the end of the day, they are only as accurate as the patterns.

Phil