High Altitude Operation Modifications
83ford8Article No. 83-19-18
ALTITUDE MODIFICATION FOR SEA LEVEL CALIBRATIONS - (4.9L) VEHICLES OVER 8500 LB. GVW
LIGHT TRUCKS 1984 E & F SERIES
CALIBRATIONS: 9-77J-R12, 9-77S-R10, 9-78J-R00, 9-78J-R11
These are modifications for subject sea level calibrations over 8500 lb. GVW that will be operated at altitude.
Service modifications for driveability concerns have been developed for sea level calibrated engines which will be principally operated in high altitude areas (over 4000 feet). The following modifications are allowed:
1. Remove the PCV valve EV-76 (D8DE-6A666-AA) and replace it with valve EV-77 D8TZ-6A666-A.
2. Advance the ignition initial timing 4~ from the nominal setting per the procedure outlined in the Truck Shop Manual.
3. Raise the vehicle.
4. Remove the transmission vacuum diaphragm attaching bolt, clip and attaching hose.
5. Remove the production transmission vacuum diaphragm and throttle valve (TV) rod and retain the TV rod. Replace the diaphragm with an altitude compensating diaphragm, D8AZ-7A377-A, using the retained TV rod.
6. Re-install the original attaching clip and bolt and torque to specification. Re-install the attaching hose.
7. Lower the vehicle.
8. Check the idle and hi-cam speeds and reset to the decal specifications, if necessary.
NOTE: The customer should retain the removed PCV valve and re-install it If the vehicle is returned to sea level operation. The new transmission diaphragm is self-compensating for both sea level and altitude and does not need to be removed.
Obtain an Authorized Modifications decal and list the date, dealer number and summary of alterations performed. Select a prominent place adjacent to the Vehicle Emission Control Information decal suitable for installing the Authorized Modifications decal. Clean the area, install the decal and cover it with a clear plastic decal shield.
PART NUMBER PART NAME CLASS
DBTZ-6A666-A PCV Valve A
D8AZ-7A377-A Altitude Compensating AM
Diaphragm
OTHER APPLICABLE ARTICLES: None
WARRANTY STATUS: Reimbursable within the provisions of the Warranty and Policy Manual.
OPERATION: M
TIME: "Actual Time" as defined in the Warranty and Policy Manual. DLR. CODING: Basic Part No. DRIVE Code: H7