As part of our engine reconditioning/rebuilding process, we measure the conrod “big-end” and “little-end” tunnels for size, shape & any distortion.
In some cases these are within the manufacturer’s tolerances and no further work is required. If issues are found, in the case of the “big-end tunnel”, it can be resized by machining the parting faces of the cap & rod, to close up the tunnel size, which is then finish honed to the desired tolerance.
The two most common types of “little-end” you can have in a conrod are Bushed (Fully Floating) and Press Fit. In the case of a bushed conrod, if there is excessive clearance in the little-end bush, or it is out of shape, then we would replace the bushes and resize them to suit the clearance that the gudgeon/piston pin requires.
For a Press Fit set up, we check that the “little-end” is round and true and has sufficient interference with the gudgeon/piston pin, replacing the conrod where necessary.