LINK A 9W8937 - Caterpillar

All 1100 Series, 3100 Series, 3200 Series EnginesDescription of Change: New reconditioning specifications for cylinder bores have been released for the above engines. The new specifications give increased clearance for the pistons in reconditioned engines to decrease piston scuffing and seizure. The new specifications are to be used only when the cylinder bores have sleeves or are machined to accept oversize pistons. The specification for cylinder bores in new blocks, which is 114.313 + 0.025 - 0.013 mm (4.5005 + .0010 - .0005"), has not been changed.
Adaptable To: The new reconditioning specifications are adaptable to all the above engines. The nominal dimension is the desired dimension after the block has been machined. Each cylinder bore must be inspected at four vertical locations; two measurements, 90° apart, must be made at each location with a dial bore gauge. The gauge must be accurate to 0.0025 mm (.0001"). The machined bore must be within specification at each point measured.
It is important to chamfer the bottom of each cylinder bore after machining the bore to prevent scuffing of the piston skirt. See the article, "Check Cylinder Bores For Chamfer During Reconditioning," on page 5 of the February 14, 1983 Service Magazine.
Add this information in the appropriate Service Manuals. It will be added to the Service Manuals during their revisions.