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, (fig. 1). 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, (fig.
2 & 3).
Most
light weight 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, (fig. 4). 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, (fig. 5). Remove burrs with a small file.