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.

3. Check engine idle and compare to specifications on the underhood label. If necessary, adjust curb idle speed. On models with Idle Speed Control (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:

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.