Oil Ring Installation with Roll Pin Locator
KB long rod and stroker pistons often have very short compression heights. The resulting short distance between the piston head and wrist pin crowds the rings so that the oil ring must be positioned over the wrist pin hole. The bottom oil ring rail must span a 3/4" gap and must not be allowed to migrate into the oil groove gap.
Many solutions for keeping the ring out of the oil groove gap and pin bore area have been tried. We feel the roll pin locator design gives the best oil control with the least added weight. The time required to slightly modify a lower oil ring rail for each piston is nominal. All that is needed is clearance for the 1/16" roll pin.
Most lightweight ring expanders will slip over the roll pin. Do not butt expander ends against the roll pin. Note that the oil ring expander does not need to be positively located, it only needs to provide clearance for the roll pin.
Be sure the top oil ring rail is free to rotate on the piston. Grinding the bottom oil ring rail is usually done on a bench grinder that has a nice square stone, then using a small file to remove any burrs.