ALTITUDE PERFORMANCE ADJUST. CONVERSION OF SYSTEM

The 1982 Chevrolet's equipped with 5.7L V8 diesel engines will be manufactured with either high or low altitude diesel systems. A vehicle with a high altitude system will be invoiced with option NA6. The type of system can also be identified by the emission label attached to the fan shroud. The label will indicate that the vehicle was designed for principal use at either high or low altitude.

These adjustments are considered Altitude Performance Adjustments and apply only to in-use vehicles. They should not be used to modify vehicles prior to sale.

Dealers must not sell vehicles with low altitude systems for principal use at high altitude.

CONVERSION OF LOW ALTITUDE SYSTEM TO HIGH ALTITUDE

Dealers in high altitude areas should encourage owners who have moved to high altitude counties to purchase the service adjustment procedure outlined below, which is considered an owner maintenance expense. See attachment for a list of counties which the Environmental Protection Agency has designated as high altitude counties.

1. Replace the EGR valve vacuum control assembly (Figure 1) with the assembly shown in the parts information.

2. Install magnetic tachometer probe, run engine until it is at operating temperature. Set idle speed to specifications, turn engine off.

3. Remove air cleaner and air crossover assemblies and install screen covers J-26996-2.

4. Install shop towel in the intake manifold valley area under the injection pump head to absorb any fuel leakage. Remove housing pressure tap plug and seal located on the rear of the pump (Figure 2).

5. Assemble locknut and new seal ("O" ring) to metering valve stop screw as shown.

6. Install assembly in injection pump until locknut contacts pump housing. Tighten locknut.

7. Place transmission in park, turn A/C off and start engine.

8. Loosen locknut and slowly turn metering valve stop screw clockwise until idle speed drops approximately 10 rpm.

9. Turn metering valve stop screw counterclockwise three (3) turns on wagons and 2 1/2 turns on all except wagons and tighten locknut.

10. Check installation for fuel leaks and remove shop towel from intake valley.

11. Turn engine off.

12. Remove magnetic tachometer probe and screened covers from intake manifold and reinstall parts removed.

13. Type or print with ballpoint pen the dealer code and date in the space provided on the supplemental emission control label, P/N 14057201 or equivalent, Figure 3 (part of kit). The label must be placed next to the existing underhood emission control information label to the extent possible. The label should not be affixed to any equipment that can be easily detached from the vehicle. Wash off the area with soap and water, dry thoroughly, and apply the new label.

PARTS INFORMATION

Part P/N ----- --- 1. EGR Valve Vacuum Control Assembly High Altitude Appli- cation

All Models Except Wagons 3-Speed A/T 22515542 or equivalent

Wagon with 3-Speed A/T 22515167 or equivalent

Label 14057201 or equivalent

2. Altitude Adjustment Kit 22516487 or equivalent

Kit Contents Quantity

Locknut 1 Seal 1 Metering Valve Screw 1 Label 1 (See Figure 3)

SUGGESTED TIME

The suggested time to perform High Altitude adjustment and part replacement procedure listed above is 0.4 hour labor.

CONVERSION OF HIGH ALTITUDE VEHICLES TO LOW ALTITUDE

Dealers should advise owners moving to low altitude areas that they should purchase the service adjustment procedure outlined below which is considered an owner maintenance expense.

1. Replace the EGR valve vacuum control assembly (Figure 1) with the assembly shown in the parts information.

2. Remove air cleaner.

3. Determine if the injection pump contains a pressure tap plug or a metering valve stop screw (Figure 2).

4. If equipped with a pressure tap plug go to Step 6.

5. If equipped with a metering valve stop screw, remove air crossover, loosen locknut and turn stop screw out (counter-clockwise) four to five times. Tighten locknut and install crossover.

6. Install air cleaner.

7. Type or print with ballpoint pen the dealer and code in the space provided on the supplemental emission control label, P/N 14055121 or equivalent (Figure 4). The label must be placed next to the existing underhood emission control information label to the extent possible. The label should not be affixed to any equipment that can be easily detached from the vehicle. Wash off the area with soap and water, dry thoroughly, and apply the new label.

PART P/N ---- --- 1. EGR Valve Vacuum Control Assembly Low Altitude Application

All Models Except Wagon 3-Speed A/T 22514746 or equivalent Wagon With 3-Speed A/T 22512323 or equivalent

2. Label (See Figure 4) 14055121 or equivalent

SUGGESTED TIME

The suggested time to perform the Low Altitude adjustment and part replacement procedure listed above is 0.4 hour labor.

DESIGNATED HIGH ALTITUDE COUNTIES* Requiring High Altitude Emission Control

State of Arizona State of Nevada

Apache Carson City Humboldt Navajo Douglas Lander Elko Lyon State of Colorado Esmeralda Mineral Eureka Storey Adama Jefferson White Pine Alamosa Lake Arapahoe La Plate Archuleta Larimer State of New Mexico Boulder Las Animas Bernalillo Mora Chaffee Lincoln Catron Rio Arriba Clear Creek Mesa Colfax Sandoval Conejos Mineral Curry San juan Costilla Moffat DeBaca San Miguel Crowley Montesuma Grant Sante Fe Custer Montrose Guadalupe Sierra Dolores Morgan Harding Socorro Delta Ouray Lincoln Taos Denver Park Los Alamos Torrance Douglas Pitkin Luma Union Eagle Pueblo McKinley Valencia Elbert Rio Blanco El Paso Rio Grande Fremont Routt State of Oregon Garfield Saguachee Gilpin San Juan Lake Grand San Miguel Gunnison Summit State of Utah Hinedalee Teller Beaver Piute Herfano Washington Box Elder Rich Jackson Weld Cache Salt Lake Carbon San Juan Daggett Sanpete State of Idaho Davis Sevier Duchesne Summit Bannock Custer Emery Tooele Bear Lake Franklin Grand Uintah Bingham Fremont Iron Utah Blaine Jefferson Juab Wasatch Bonneville Madison Kane Wayne Butte Minidoka Millard Weber Camas Oneida Morgan Caribou Power Cassia Teton State of Wyoming Clark Valley Albant Matrona Carbon Niobrara State of Montana Converse Park Beaverhead Madison Fremont Platte Deer Lodge Meagher Goshen Sublette Gallstin Park Hot Springs Sweetwater Jefferson Silver Bow Johnson Taton Laramie Uinta State of Nebraska Lincoln Weston Banner Sioux Kimball

* Counties which have substantially all of their area bove 4000 ft. Ref. Federal Reigster, Vol. 42, No. 76, April 20, 1977, pg. 20464

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.