Great!.
Andover sent me the technical pecification:
"Inspection
Visually check the cylinder barrel for cracks and corrosion. Inspect the threads and studs to ensure they are not damaged or stripped.
Check the cylinder bore for scuffing and scoring. Bore wear is often evident in the form of a wear ridge at the top of the bore. This ridge marks the limit of piston ring travel.
Measurement
Measure the diameter of each cylinder bore, front to back, in two places:-
1) within 1” of the top, front to rear
2) near the bottom below the piston ring swept area, front to rear.
Measure the diameter of each piston:-
3) at right angles to the gudgeon pin axis just above the base of the skirt.
Assessment
If the bore is in acceptable condition, the difference between the two measurements (1 & 2, above) should not exceed 0.005” .
By comparing the measured piston diameter (3, above) with the bore diameter the clearances can be calculated and assessed to see if they are within specification.
Rectification
If the cylinder walls are badly scuffed or scored or if the piston -to-barrel clearance is excessive then the cylinder will need to be re-bored by an engine overhaul specialist. New oversize pistons will be re- quired.
N.B. It is important that the re-bore specialist is given both the pistons and cylinder barrel.
The pistons (even new ones) must be accurately measured to suit the re-bored cylinder. The correct piston to barrel clearance for GPM/Gandini pistons is 0.0040 to 0.0045 inches .
If the cylinders and pistons are within specification it may only be necessary to re-new the piston rings. In this case the bores should be honed to allow the new rings to bed in correctly and provide the best possible seal. This honing operation is normally left to an experienced motor engineer.
The correct piston ring end gap for GPM/Gandini pistons is 0.009 to 0.017 inches for all three rings.
Tools
Three good quality tools are required for the measuring operations described above:-
a. An external micrometer with a range of 2 to 3 inches to measure 750 pistons or a range of 3 to 4 inches to measure 850 pistons.
b. A telescope gauge with a range of 2 to 3.5 inches.
c. A set of feeler gauges."
Thank you.
Piero