What is the standard range for piston ring three gaps?

[Santos]

Introduction to the standard range of piston ring three gaps: end gap 0.25-0.5mm, side gap 0.03-0.06mm, back gap 1mm; size requirements vary for different engines. The three gaps of piston rings refer to the opening (ring gap) clearance, axial clearance (side gap), and radial clearance (back gap). Below is an introduction to the three gaps of piston rings: 1. Measurement of end gap: The end gap is the clearance at the opening when the piston ring is installed in the cylinder, to prevent the piston ring from seizing due to thermal expansion. When checking the piston ring end gap, place the piston ring flat in the cylinder, push it flat with the piston top, and then measure the opening clearance with a feeler gauge, generally 0.25-0.50mm. The first ring has a larger end gap than the others due to higher working temperatures. 2. Measurement of side gap: The side gap refers to the up and down clearance of the piston ring in the ring groove. A too large side gap affects the sealing function of the piston, while a too small side gap can cause the piston ring to seize in the groove. When measuring, place the piston ring in the ring groove and measure with a feeler gauge. The first ring, due to higher working temperatures, generally has a value of 0.04-0.10mm, other gas rings generally 0.03-0.07mm, ordinary oil rings have a smaller side gap, generally 0.025-0.07mm, and composite oil rings have no side gap. 3. Measurement of back gap: The back gap refers to the clearance between the back of the piston ring and the bottom of the piston ring groove after the piston is installed in the cylinder, generally represented by the difference between groove depth and ring thickness, usually 0.30-0.40mm. Ordinary oil rings have a larger back gap; a common practice is to install the piston ring in the groove, and if it is below the ring land and can rotate freely without sticking, it is considered suitable.