Article 970 - Cold Engine Stall or Hesitation on Acceleration

TSB #56 - December 16, 1966
(1967 390-2V Thermactor Automatic Transmission Equipped Units)

Customers with subject units have complained of engine stall or hesitation on acceleration during the engine warm-up period. This complaint is caused by a carburetor fuel-air mixture which is too lean during engine warm-up to satisfy engine requirements. The following carburetor modifications must be performed to correct this problem cause:

    1. Enlarge the high speed air bleeds to 0.039 inch. (Illus. S1155-A).
    2. Enlarge the accelerator pump jets to 0.026 inch. (Illus. S1156-A).
    3. Raise the fuel level to a 3/4" we level setting.
    4. Revise the choke cover adjustment to a '2 notches rich' setting.
To enlarge the high speed bleeds and the accelerator pump jets, remove the booster support from the carburetor and use the specified size drill * in a pin vise. Coat the drill tip with light grease to retain a majority of the filings and slowly rotate the drill through the hole. Complete the drilling operation by thoroughly blowing out the booster support with compressed air to remove any chips.

* No. 71 Drill - 0.026 Inches
No. 61 Drill - 0.039 Inches

C7AF-9510-Z AND C70F-9510-M
High Speed Bleed0.029 Inch0.039 Inch
Accelerator Pump Jet0.024 Inch0.026 Inch
Choke SettingIndex2 Notches Rich
Wet Fuel Level Setting7/8 Inch3/4 Inch

Illus. S1155-A
Click to enlarge
Illus. S1156-A
Click to enlarge

Oper: SP9510-C-67
Time: 0.5 hrs.