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Procedure II

All carbureted H.D. Gasoline Powered Vehicles should be adjusted to low altitude specifications.

^ 5.7L (LT9)

1. Reset base timing to specification on the low altitude Emission Control Information Label.

2a. Manual Transmission Do not adjust the carburetor vacuum break.

2b. Automatic Transmission Reset carburetor vacuum break to 24 degrees.

3. Reset base idle speed to specification on the low altitude Emission Control Information Label.

4. Reset fast idle speed to specification on the low altitude Emission Control Information Label.


^ HEAVY DUTY GASOLINE EMISSION PACKAGES (CARBURETED MODELS ONLY) 4.8L (L25) AND 7.4L (LE8) ENGINES

1. Reset base timing to specification on the low altitude Emission Control Information Label.

2. Reset idle speed to specifications on the low altitude Emission Control Information Label.

^ FEDERAL 6.2L DIESEL ENGINE (LH6) and (LL4)

Vehicles designed for principal use at high altitude perform satisfactorily at low altitude without excessive smoke levels and need not be adjusted for extended operation at low altitude.
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