Selecting Gear Ratios

In order to receive the proper gear ratio for your drive, you must use table below:

350 cubic inch, 5.7 liter, 350 MAG, 5.0 EFI engines

1.47 ratio, 1.50 ratio

Carbureted 305 cubic inch, 5.0 liter carb, 4.3 liter EFI
and Inline 6 engines

1.62 ratio, 1.65 ratio

4.3 liter V-6 engines with carb

1.81 ratio, 1.84 ratio

3.7 liter and 470, 485 and 488 4-cylinder engines

1.81 ratio, 1.84 ratio

120, 140, 3.0 liter engines

1.94 ratio, 1.98 ratio

Please note that Mercruiser changed their gear ratios somewhat in the mid-1980s (for example a V-8 gear ratio used to be 1.50, but Mercruiser now uses 1.47 ratios. Select the gear ratio based on your engine size).