Carburetor - Holley 418C Rough Idle/Stalls
84ford14Article No. 84-10-10
ROUGH IDLE/STALLS (WARM) 5.0L H.O. HOLLEY 4180-C
FORD 1983-84 MUSTANG
LINCOLN-MERCURY 1983-84 CAPRI
CALIBRATIONS: All 5.0L H.O. calibrations equipped with Holley 4180-C except for - 3-21A and 3-21P.
Rough idle/stalls warm engine may be due to contamination in the secondary idle circuit resulting in a lean condition.
The above concerns may result from a lean condition in the secondary idle system due to contamination.
1. To verify that the above condition is present, perform the Idle Mixture Setting Procedure - Propane Gain through Step II-C as described in Attachment 2 to this article. If the measured speed gain is to specification, no further action in this bulletin applies, except continue with Step G of Attachment 2 to return the vehicle to the as received condition for calibrations 4-21A and 4-21P, refer to Shop Manual for appropriate diagnostics.
2. If an idle mixture adjustment is required, remove the carburetor from the vehicle and cover the intake manifold.
CAUTION: THE CARBURETOR IS A PRECISION FLOW METERING DEVICE AND MUST BE HANDLED WITH CARE.
FIGURE 15:
3. Drain the fuel from the carburetor, then detamperproof the primary and secondary idle mixture screws as follows:
^ Invert the carburetor and center punch the throttle body as noted in Figure 15, approximately 5/16 inches from the face of each screw cavity.
^ Using a #30 (.128 inch diameter) drill bit, drill approximately 1/16 inch deep. Then tip the drill back such that the bit is pointed toward the screw cavity face (tip approximately 60_ with respect to the throttle body face). Drill through until the bit contacts the tamperproof plug.
^ With a 1/8 inch or less diameter punch gently tap out the tamperproof plugs.
NOTE: On some of the 1983 carburetors the primary plugs differed in diameter and length from the secondary plugs. Save the plugs for re-use. Blow out chips with shop air.
FIGURE 16:
4. Remove the secondary diaphragm link E-clip and save for re-installation (Figure 16). Move the link off the lever post. Remove and discard the primary to secondary link cotter pin, then remove and save the link. This allows ease in cleaning the secondary bores and plates as described in Steps 6 and 7.
5. Remove the eight throttle body retaining screws and save for re-installation. Carefully separate the throttle body from the main body. Remove and discard the throttle body to main body gasket.
FIGURE 17:
6. Thoroughly spray Carburetor and Combustion Chamber Cleaner on the throttle body primary and secondary bores and on the throttle plates. Invert the throttle body and spray into the primary and secondary idle discharge channels (Figure 17). Allow to soak for 15 minutes.
7. After soak, loosen any remaining deposits with a small clean brush and re-apply cleaner. Blow out the passages with shop air.
8. Remove the secondary idle mixture screws, wipe off all remaining residue from the screw taper and apply shop air to the idle discharge port.
NOTE: Do not remove the primary mixture screws.
9. Re-install the secondary mixture screws until they are lightly seated then turn the screws counterclockwise 1-1/2 turns.
NOTE: Make sure that the screws are turned equal amounts.
Re-install the secondary tamperproof plugs and set aside the throttle body for installation later.
FIGURE 18:
10. Spray the cleaner into the secondary idle air bleeds (Figure 18) and allow to soak during the following steps.
11. Remove the four secondary bowl screws and remove any excess gasket material from the screw heads. Set aside for re-assembly later.
FIGURE 19:
12. Carefully pry the secondary bowl from the main body by placing a large screw driver between the float level adjustment screw and the bowl vent boss (Figure 19). Use extreme care to prevent bending the primary to secondary fuel transfer tube.
13. Spray Automatic Choke Cleaner on gasket material stuck to the carburetor bowl at the main body sealing surface and at the mounting screw location. Allow to soak and carefully scrape the excess gasket material away. Re-spray the bowl to flush away any loose gasket material. Blow out with shop air.
14. Remove and discard the six metering plate screws.
15. Carefully pry the secondary metering plate away from the main body and discard.
16. Spray the gasket material stuck to the main body with choke cleaner. Allow to soak for 5 minutes.
17. Carefully scrape away the gasket material from the main body. Do not be concerned over bending the back up plate as it too will be replaced.
18. Make sure that all excess gasket material is removed from the main body. Spray with choke cleaner then blow out all passages with shop air.
FIGURE 20:
19. Procure carburetor service kit number E3PZ-9590- D and re-install the appropriate gaskets, back-up plates and metering plates as shown in Figure 20. Torque the six new shorter clutch drive metering plate screws (supplied in kit) to 18 in.lbs.
20. Re-install the primary to secondary fuel transfer tube to the secondary bowl. Make sure to use the new O-ring provided in the service kit. Re-install the secondary bowl using the four existing screws and the new screw gaskets. Torque the screws to 50 in.lbs.
FIGURE 21:
21. Re-install the throttle body using the new throttle body gasket provided in the kit. Make sure that the accelerator pump lever and the secondary diaphragm link are properly assembled during this procedure.
Make sure the secondary diaphragm link E-clip is installed on the lever post. Torque the eight throttle body retaining screws to 50 in.lbs. Reinstall the primary to secondary link, then reinstall the new cotter pin, assuring proper orientation as noted in Figure 21.
22. Re-install the carburetor to the engine. Make all the appropriate fuel, electrical and vacuum connections. Start the engine and check for fuel leaks. Turn engine off and make corrections as necessary.
23. Continue with the Propane Gain Procedure described in Attachment 2.
The above mentioned service kit E3PZ-9590-D (Holley number 85R-7499) consists of the following:
Holley
Qty. Part No. Ford Part No.
Sec. Metering Plate (1) 34R-10465
Sec. Met. Plate Screws (6) 5R-691
Gasket-Sec. Met. Plate (1) 8R-1437 D9PZ-9A518-A
Gasket-Sec. Met. Body (1) 8R-1908 D9PZ-9A518-E
Sec. Met. Plate-Back-Up (1) 34R-1993
O-ring (Fuel Trans. Tube) (2) 27R-109 EAD-99502-A
Gasket-Fuel Bowl Screws (4) 8R-1994 E3PZ-9592-A
Gasket-Throttle Body (1) 8R-1748 D9PZ-9516-A
Cotter Pin-(Pri. to Sec. Link) (1) 48R-183
Attachment 2: Idle Mixture Setting Procedure - Propane Gain
I. Vehicle Preparation
A. Apply the parking brake and block the wheels.
B. Verify that timing is set to specification.
C. Remove the hose at the dump valve and plug it. Connect a slave hose from the dump valve vacuum fitting to an intake manifold fitting.
D. Remove the PCV valve from the rocker cover grommet and move away from the crankcase vapors.
E. Connect tachometer, Rotunda Model 059-00007, 099-00003, or equivalent.
NOTE: The use of an accurate tachometer is critical to achieve correct adjustment.
F. Disconnect the flexible fresh air tube from the air cleaner duct or adaptor. Using propane enrichment tool, Rotunda Tool T75L-9600-A or equivalent, insert the tool hose approximately 3/4 of the way into the duct or fresh air tube. If necessary, secure the hose with tape.
G. Locate the crankcase vent hose (filler cap to air cleaner) and disconnect at the air cleaner end, allowing the hose to vent to underhood air during idle fuel/air mixture check.
H. Check curb idle rpm and reset to specification as required.
II. Propane Enrichment Method
NOTE: Leave all vacuum signal hoses attached to the air cleaner assembly when relocating the assembly to perform carburetor adjustments. The air cleaner assembly must be in place and the air charge temperature switch must be connected when measuring engine speeds.
CAUTION: PROLONGED ENGINE IDLING CAN RESULT IN CATALYST OVERHEATING AND EXCESSIVE UNDERBODY TEMPERATURES.
A. With the transmission in Neutral, run the engine at approximately 2500 rpm for 15 seconds before each mixture check.
B. With the engine idling at normal operating temperature, place the transmission selector in Neutral. Gradually open the propane tool valve and watch for engine speed gain, if any, on the tachometer. When the engine speed reaches a maximum and then begins to drop off, note the maximum amount of speed gain. The propane cartridge must be in vertical position.
NOTE: If the engine speed will not drop off, check the propane cartridge gas supply. If necessary, repeat Stops A and B with a new propane cartridge gas supply.
C. Compare measured speed gain to specified gain (20-40 rpm).
FIGURE 22:
D. If the measured speed gain is higher than the speed, gain specification, turn the primary mixture screws counter clockwise (rich) in equal amounts while simultaneously repeating Steps A, B, and C until the measured speed rise meets specification.
NOTE: The mixture screws can be adjusted by a tool with a 3/32 inch Allen head, such as Textron part no. 358 or equivalent. Reference Figure 22.
E. If the measured speed gain is lower than the speed gain specification, or there is no speed gain, turn the primary mixture screws clockwise (lean) in equal amounts while simultaneously repeating Steps A, B and C until the measured speed rise meets the specification.
F. After the gain has been set, install the primary concealment plugs.
G. Remove the equipment used to perform this procedure. Reconnect the PCV valve and the hose at the dump valve. Reinstall the air cleaner and associated vacuum hoses.
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
E3PZ-9590-D Service Kit CG
OTHER APPLICABLE ARTICLES: None
WARRANTY STATUS: Reimbursable within the provisions of the Warranty and Policy Manual.
OPERATION: SP9510F83
TIME: 1.4 Hrs. DLR. CODING: Basic Part No. 9510 Code: 49