H1 Oil Pump
Crank to oil pump ratio is somewhere
near 2.5666:1,
2.56 turns (revolutions) of the crank to 1 turns (revolutions) of the pump.
H2B/C
Oil Pump
Darth here, I have learned that standard #016 and #017 O-Rings will fit the end caps on the H2B/C pumps. #016 on the throttle cam end and the #017 on the line side end.
S/H Series Difference
The S and H series
pumps differ with drive gear, cam plate and direction of rotation.