What is normally used to maintain the correct piston-to-cylinder clearance?
The clearance between the piston and cylinder is maintained by
the piston rings, the ring centers the piston within the cylinder
bore and is the device that seals the cylinder bore and creates and
maintains the pressure created by the piston movement in the bore.
When assembling an engine you will need to check and set end gap of
the rings, this is done by centering the new ring in the bore and
measuring the gap between the ring ends, you can measure this
distance with feeler gauges and adjust by filing the ends of the
rings to increase to the recommended tolerance, this tolerance is
measured in .000 of an inch and different engines require different
end gaps. This end gap is determined by the diameter of the bore
with the greater the bore diameter than the greater the end
gap,.