RPM = MPH X Gear Ratio X 336 divided by Tire Diameter (inches)

**Rolling diameter of a tire differs from standard diameter. Measure rolling
diameter by marking rear tire and ground with chalk and driving car forward
one tire revolution. Divide measurement by Pi (3.1416)**

MPH = RPM X Tire Diameter (inches) divided by Overall Gear Ratio X 336

**Convert from:**

**Miles to Kilometers, Multiply by 1.609344**

**Liters to Cubic Inches, Multiply by 61.023744**

**Inches to Millimeters, Multiply by 54.4**

**Millimeters to Inches, Multiply by .0393701**

**
Displacement: (cubic inches) =
Bore (inches) Squared X Stroke (inches) Xnumber of Cylinders X .7854**

**
Displacement: (cubic inches) = Pi
(3.1416) X Rdius of Bore Squared X Number of Cylinders X Stroke (inches)**

Rear End Ratio = Flywheel Turns X 2 divided by Rear Wheel Turns

**Jack only one rear wheel off the ground and shift transmission into high.
Formula applies only to standard three-speed transmission that has high gear
as a straight through drive. If car has overdrive, lock it out. Rotate wheel
one full turn and count flywheel turns to the fraction.**

Transmission Ratio = Flywheel Turns X 2 divided by Rear Wheel Turns X Rear End Ratio

**Shift transmission into either first, second or high gear with overdrive,
depending on which gear ratio you want to find. Follow procedure for "Rear
End Ratio" formula above.**