Checking Solenoid Plunger Travel

Transcription

1 1985 Chevy Truck EL Camino V L Page 1 Carburetor: Adjustments Carburetor Calibration E2M & E4M Series Mixture Control Solenoid Plunger Travel Checking Solenoid Plunger Travel OTE: Mixture control solenoid plunger travel should be checked before proceeding with any carburetor adjustments or disassembly. OTE: This procedure requires the use of float Gauge JD , BT-7720, or equivalent. It may be necessary to file or grind material off the gage o allow it to enter the vent hole freely. 1. With the engine OFF, remove the air cleaner and gasket. 2. Insert float gage in the vertical "D" shaped vent hole in the air horn casting, next to the Idle Air Bleed Cover, (Figure 1). 3. Press down on gauge and release, be sure the gauge moves freely--does not bind. 4. With gage released--the plunger in the UP position--record the gauge reading--in inches--at the upper edge of the air horn casting. 5. Press down lightly on gage until the plunger is in the DOWN position. Record the gauge reading--in inches--at the upper edge of the air horn casting. 6. Subtract gage UP position (Step 4) from gage DOWN position (Step 5), and record difference as "total plunger travel". 7. If total plunger travel (Step 6) is between 2/32" and 6/32', proceed to Idle Air Bleed Valve Adjustment, If it is not between 2/32" and 6/32", adjust mixture control solenoid plunger travel. Mixture Control Solenoid Adjustment Procedure 1. Remove air horn, mixture control solenoid plunger, air horn gasket and plastic filler block, using normal service procedures. 2. Remove throttle side metering rod. Install mixture control solenoid gaging Tool JD , BT-8253-A, or equivalent, over the throttle side metering jet rod guide, and temporarily reinstall the solenoid plunger into the solenoid body. Installing Mixture Control Solenoid Gauging Tool

2 1985 Chevy Truck EL Camino V L Page 2 Adjusting Lean Mixture Solenoid Screw 3. Holding the solenoid plunger in the DOWN position, use Tool JD , BT-7928, or equivalent, to turn lean mixture (solenoid) screw counterclockwise until the plunger breaks contact with the gaging tool. The adjustment is correct when the solenoid plunger is contacting BOTH the SOLENOID STOP and the GAGING TOOL. If the total difference in adjustment required less than 3/4 turn of the lean mixture (solenoid) screw, the original setting was within the manufacture's specifications. 4. Remove solenoid plunger and gaging tool, reinstall metering rod and plastic filler block. 5. Invert air horn and remove rich mixture stop screw and rich authority adjusting spring from bottom side of air horn, using Tool JD , BT-7967A or equivalent. Removing Rich Mixture Stop Screw Removing Lean Mixture & Rich Mixture Stop Screws 6. Remove lean mixture screw plug and rich mixture stop screw plug from air horn using a suitably sized punch. 7. Reinstall rich mixture stop screw and rich authority adjusting spring in air horn and bottom lightly, then back screw out 1/4 turn. 8. Reinstall air horn gasket, mixture control solenoid plunger and air horn to carburetor.

3 1985 Chevy Truck EL Camino V L Page 3 Adjusting Rich Mixture Stop Screw 9. Insert external float gauge in vent hole and with TOOL JD , BT-7220 or equivalent, adjust rich mixture stop screw to obtain 4/32" total plunger travel. Installing Lean & Rich Mixture Stop Screw Plugs 10. With solenoid plunger travel correctly set, install plugs (supplied in service kits) in the air horn, as follows: a. Install plug, hollow end down, into the access hole to lean mixture solenoid screw and use suitably size punch to drive plug into the air horn until the top of the plug is even with the lower edge of the hole chamfer. Plug must be installed to retain the screw setting and to prevent fuel vapor loss. b. Install plug, with hollow end down, over the rich mixture stop screw access hole, and drive plug into place so that the top of the plug is 1/16" below the surface of the air horn casting. Plug must be installed to retain screw setting. Test Description NOTE: A cover is riveted in place over the idle air bleed valve, and the access holes to the idle mixture needies are sealed with hardened plugs, to seal the factory settings, during original equipment production. These items are NOT to be removed unless required for cleaning, part replacement, improper dwell readings (Step 4, below), or if the "System Performance Check" indicates the carburetor is the cause of the trouble. 1. Before proceeding: a. Set Parking brake and block drive wheels. b. Disconnect and plug hoses, as directed on Emission Control Information Label under the hood. c. Check ignition timing as shown on the Emission Control Information label. d. Connect dwell meter and tachometer as noted in "System Performance Check" chart. 2. Start engine, and with transmission in Park or Neutral, run engine at idle until fully warm and a varying dwell is noted on the dwell meter. It is essential that the engine is operated for a sufficient length of time to ensure that the engine coolant and the oxygen sensor in the exhaust, are at full operational temperature.

4 1985 Chevy Truck EL Camino V L Page 4 3. Check engine idle and compare to specifications on the underhood label. If necessary, adjust curb idle speed. On models with Idle Speed Contro (ISC) motor no curb idle adjustment is possible as curb idle speed is controlled by ECM. If idle speed is out of specification, refer to ISC ADJUSTMENT UNDER ADJUSTMENT PROCEDURES section for correct setting procedure. 4. With engine idling in Drive (Neutral for manual transmission), observe dwell reading on the 6 cylinder scale. If varying within the 10-50' range, adjustment is correct. If NOT, proceed to step 5. Figure A Removing Staked Cover Figure B Removing Idle Air Bleed Cover Rivets 5. IDLE AIR BLEED VALVE COVER REMOVAL To gain access to the idle air bleed valve for identification, adjustment or servicing, it is necessary to remove the idle air bleed valve cover. If cover is staked in place, see Figure A. 6. If cover is riveted, remove as follows starting with Step "A" below. a. To remove riveted cover start with engine off, cover internal bowl vents and air inlets to the bleed valve with masking tape or equivalent. Cover carburetor air intakes with masking tape to prevent metal chips from entering carburetor and engine. b. Carefully align a No. 35 (.110") drill bit on one of the steel rivet heads holding the idle air bleed valve cover in place. Drill only enough to remove rivet head. See Figure B. Drill the remaining rivet head located on the other side of the tower. Use a drift and small hammer to drive the remainder of the rivets out of the idle air bleed valve tower in the air horn casting. Use care in drilling to prevent damage to the air horn casting. Lift out cover over the idle air bleed valve and remove the rivet pieces from inside the idle air bleed valve tower. c. CAUTION: For the next operation, safety glasses must be worn to protect the eyes from possible metal shaving damage. Using shop air, carefully blow out any remaining chips from inside the tower. DISCARD COVER AFTER REMOVAL. A missing cover indicates that the idle air bleed valve setting has been changed from its original factory setting. Idle Air Bleed Valve-Letter ID Location

5 1985 Chevy Truck EL Camino V L Page 5 d. With cover removed, look for presence (or absence) of a letter identification on top of idle air bleed valve. e. If NO identifying letter appears on top of the valve, begin PROCEDURE A, If the valve IS identified with a letter, begin PROCEDURE B. Procedure A (Without Letter on Idle Air Bleed Valve) Installing Idle Air Bleed Valve Gauging Tool. rocedure A (No Letter on Idle Air Bleed Valve) Positioning Idle Air Bleed Valve 1. PRESETTING THE IDLE AIR BLEED VALVE to a gage dimension is necessary if the idle air bleed valve was serviced prior to on-vehicle adjustment. a. Install idle air bleed valve gaging Tool JD , BT-8253-B, or equivalent, in throttle side "D" shaped vent hole in the air horn casting. The upper end of the tool should be positioned over the open cavity next to the idle air bleed valve. b. While holding the gaging tool down lightly, so that the solenoid plunger is against the solenoid stop, adjust the idle air bleed valve so that the gaging tool will pivot over and just contact the top of the valve. The valve is now preset for on-vehicle adjustment. c. Remove gaging tool and proceed to step 2 below. 2. ADJUSTING THE IDLE AIR BLEED VALVE (PROCEDURE A) a. To obtain correct dwell reading on vehicle, start engine and allow it to reach normal operating temperature. b. While idling in Drive (Neutral for manual transmission), use a screwdriver to slowly turn valve counterclockwise or clockwise, until the dwell reading varies within the 25-35~ range, attempting to be as close to 30~ as possible. Perform this step carefully. The air bleed valve is very sensitive and should be turned in 1/8 turn increments only. c. If, after performing Steps a and b above, the dwell reading does not vary and is not within the 25-35~ range, it will be necessary to remove the "concealment plugs and to adjust the idle mixture needles". SEE CONCEALMENT PLUG REMOVAL & IDLE NEEDLE ADJUSTMENT PROCEDURE A. Procedure B (With Letter on Idle Air Bleed Valve)

6 1985 Chevy Truck EL Camino V L Page 6 Installing Idle Air Bleed Valve Gauging Tool. Positioning Idle Air Bleed Valve rocedure B (Letter Appears on Idle Air Bleed Valve--Carburetors WITH letter identification on the idle air bleed valve are adjusted by: 1. SETTING THE IDLE AIR BLEED VALVE to a gage dimension. a. Install air bleed valve gaging tool JD , BT-8253-B, or equivalent, in throttle side "D" shaped vent hole in the air horn casting. The upper end of the tool should be positioned over the open cavity next to the idle air bleed valve. b. While holding the gaging tool down lightly, so that the solenoid plunger is against the solenoid stop, adjust the idle air bleed valve so that the gaging tool will pivot over and just contact the top of the valve. The valve is now set properly. No further adjustment of the valve is necessary. c. Remove gaging tool. Concealment Plug Removal

7 1985 Chevy Truck EL Camino V L Page 7 Removing Idle Needle Concealment Plugs 1. Remove the carburetor from engine following normal service procedures, to gain access to the plugs covering the idle mixture needles. 2. Invert carburetor and drain fuel into a suitable container. 3. Place carburetor on a suitable holding fixture, with manifold side up. Use care to avoid damaging linkage, tubes, and parts protruding from air horn. 4. Make two parallel cuts in the throttle body, one on each side of the locator points beneath the idle mixture needle plug (manifold side), with a hacksaw. 5. The cuts should reach down to the steel plug, but should not extend more than 1/8" beyond the locator points. The distance between the saw cuts depends on the size of the punch to be used. 6. Place a flat punch near the ends of the saw marks in the throttle body. Hold the punch at a 45~ angle and drive it into the throttle body until the casting breaks away, exposing the steel plug. The hardened plug will break, rather than remaining intact. It is not necessary to remove the plug in one piece, but remove the loose pieces. 7. Repeat this procedure with the other mixture needle. Idle Needle Adjustment Procedure A 1. SETTING THE IDLE MIXTURE ADJUSTMENT PROCEDURE A where correct dwell reading could not be obtained with idle air bleed valve adjustment. A. Using Tool JD B, BT-7610B, or equivalent, turn both idle mixture needles clockwise until they are lightly seated, then turn each mixture needle counterclockwise 3 turns. B. Reinstall carburetor on engine using a new flange mounting gasket, but do not install air cleaner and gasket at this time. 2. READJUSTING IDLE AIR BLEED VALVE to finalize correct dwell reading. (Only necessary if idle mixture needles required setting in Step (1), above). A. Start engine and run until fully warm, and repeat "ADJUSTING THE AIR BLEED VALVE! B. If unable to set dwell to 25-35~, and the, dwell is below 25~, turn both mixture needles counterclockwise an additional turn. If dwell is above 35~, turn both mixture needies clockwise an additional turn. Readjust idle air bleed valve to obtain dwell limits. After adjustments are complete, seal the idle mixture needle openings in the throttle body, using silicone sealant, RTV rubber, or equivalent. The sealer is required to discourage unnecessary adjustment of the setting, and to prevent fuel vapor loss in that area. On vehicles WITHOUT a carburetor mounted Idle Speed Control Motor adjust curb idle speed if necessary. Check, and only if necessary adjust fast idle speed as described on Emission Control Information label. Idle Needle Adjustment Procedure B 1. IDLE MIXTURE ADJUSTMENT B on the vehicle to obtain correct dwell readings. A. Remove idle mixture needle plugs, following instructions under CONCEALMENT PLUG REMOVAL

8 1985 Chevy Truck EL Camino V L Copyright 2007, ALLDATA 9.50 Page 8 B. Using Tool JD B, BT-7610-B, or equivalent, turn each idle mixture needle clockwise until lightly seated, then turn each mixture needle counterclockwise 3 turns. C. Reinstall carburetor on engine, using a new flange mounting gasket, but do not install air cleaner or gasket at this time. D. Start engine and allow it to reach normal operating temperature (drive wheels blocked). E. While idling in Drive (Neutral for manual transmission), adjust both mixture needles equally, in 1/8 turn increments, until dwell reading varies within the 25-30~ range, attempting to be as close to 30~ as possible. If reading is too low, turn mixture needies counterclockwise. If reading is too high, turn mixture needles clockwise. Allow time for dwell reading to stabilize after each adjustment. After adjustments are complete, seal the idle mixture needle openings in the throttle body, using silicone sealant, RTV rubber, or equivalent. The sealer is required to discourage unnecessary readjustment of the setting, and to prevent fuel vapor loss in that area. On vehicles WITHOUT a carburetor -mounted Idle Speed Control motor adjust curb idle speed if necessary.