There is no clearance of the ring to the block. The ring works in contact with the block to seal the combustion chamber and provide oil control.
Piston ring gap.
To measure the piston ring side clearance, first, install the piston ring onto the piston and place them in the cylinder bore. Use a feeler gauge to measure the gap between the ends of the ring when it is positioned in the bore. The thickness of the feeler gauge that fits snugly in the gap indicates the side clearance. Ensure that the measurements are taken at multiple points for accuracy, as the clearance can vary due to wear or manufacturing tolerances.
assuming that you have new cylinder liners and pistons or old pistons with good ring groove conditions, piston rings come with the correct/specified clearance when bought new.
Clearance volume usually refers to the volume above the piston(to the top of the block) if the piston is receased( .30'' in the hole). + vavle relief in cc's+ the volume of the head gasket.
As the piston moves up and down in the cylinder it also moves the piston rings up and down in the grooves. With the rings moving up and down it gradually increases the side clearence. Material is taken off from both the piston groove and the ring.
On the pistons, in the block. If they are bad, it's time for an engine rebuild.
excessive piston to bore clearance means that the gap (tollerance) between your piston and the sidewall of your cylinder/block is too large. usually will cause blow-by. the burning of oil, and dark exhaust smoke. also may cause the engine to have a weak compression stroke
bumping clearance is the clearance between piston and head ,piston and crank endside
Slide one of the compression rings down into the cylinder and measure the gap with a feeler gauge.
The way the question is phrased the answer is zero. But I suspect that you mean ring gap, and rule of thumb is .002 inches per inch of bore.
most auto mechanic preferred .002 clearance from piston skirt to sleeve
Piston protrusion is typically measured by placing a dial indicator on the top of the piston while it is positioned at Top Dead Center (TDC). The measurement is taken from the piston crown to the deck surface of the engine block. This measurement is important for ensuring proper clearance and compression ratio in an engine.