Calculated Industries Hot Rod Calc 8703 User Manual page 20

current, local measured weather conditions entered into
the calculator. Once you have established an air/fuel ratio
for the current track and weather conditions, calculate and
record the current ADI.
As a rule, ADI will be less than 100% for elevations
above sea level as well as for temperatures above 60° F.
Conversely, ADI will be more than 100% for temperatures
below 60° F.
As a guideline, ADI can be used to tune your engine's
air/fuel requirements when conditions change from your
baseline conditions. For each percentage point the current
ADI is above your recorded baseline ADI, your engine
will require that much more fuel. Conversely, for each
percentage point the current ADI is below your recorded
baseline ADI, your engine will require that much less fuel
to maintain the same level of performance.
Be careful! It's safer to be 3% rich than to be 1% lean.
ADI can tell you a lot about what you need to know for
carburetor jetting changes, however, you must understand
all the relationships before making a change. Surging or
hesitating will indicate that your vehicle is likely running
too lean an air/fuel ratio. If you're seeing black smoke
out the exhaust, it is likely you are running too rich an air/
fuel ratio. Combine your experience with theory, always
refer to your carburetor manufacturer's jetting size and
change instructions, and make air/fuel changes in small,
incremental steps.
Lastly, data is knowledge, and knowledge is power!
Always record your air/fuel and jet number settings along
with the Hot Rod Calc's calculated ADI and density
altitude for those last minute adjustments as weather
conditions change throughout the day or for dialing in at
different track locations.
18 — H R C ™
OT OD ALC