Mr. Gasket 8703 Hot Rod Calculator - Manual (Page 23)

U
ser
'
s
G
Uide — 21
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 carbure-
tor 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 man-
ufacturer’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.
Pressure
There are two types of commonly referenced Pressure,
absolute Pressure and Corrected Pressure.
absolute Pressure is the actual, ambient local Pressure.
There are several tools available to help you measure abso-
lute Pressure, such as altimeters, absolute barometers, and
motorsports weather stations. you do not need to know your
track’s Elevation when utilizing absolute Pressure on your
calculator.
Corrected Pressure is a measurement you might get from
the local radio station, Tv station, from the Internet, or from
a “corrected” barometer. It is corrected for sea level and is
not suitable for motorsports. Do not use corrected Pressure
on the Hot Rod Calc.
(cont'd)
UG8703E-B-inside.indd 21 3/3/2010 3:03:58 PM