The tractor cylinders had been bored out and oversize piston put in.

Once I removed the number on piston, took a compression ring off the piston, and inserted it into the cylinder I knew there was a problem.  There was a compression ring end clearance of 90 to 100 thousands.  The book specification is 20 to 30 thousands.  Either there was a lot of ware, the ring was the wrong size, or someone got carried away with a file.

To measure the pistons and cylinder's you need a 4" to 5" micrometer and a set of telescoping T gauges.  Because of the difficulty of setting the T gauge inside the cylinder, I found it easier to us it as a go-no-go gauge by using the micrometer incrementing it by 1/1000 until the gauge is to large for the cylinder.

Forensic evaluation of piston and cylinders indicate that they are 45 thousands oversize and within tolerance.