Use the chart below to determine drive ratios for 8-71 8mm pitch drive superchargers. Small block 8-71 kits are supplied standard with pulleys which will provide 14.3% underdrive. Big block kits are supplied with a 11.5% underdrive. Note that top and bottom pulleys are interchangeable.

Click Here to View
Pulley Overdrive/Underdrive Percentage Chart
for 8mm Pitch Pulleys