Fast Idle Adjustment

HOLLEY 6280 2 Bbl

Holley 6280 Carburetor Assembly:

NOTE: Refer to Specifications for curb and fast idle speeds.


1. Verify ignition timing is properly set, if timing is correct move to step 2, if not go to Ignition Timing Adjustments.
2. Disconnect and plug vacuum hose at EGR valve.
3. Disconnect and plug hose from carburetor at the heater air temperature sensor.
4. Remove air cleaner assembly, then disconnect and plug canister purge hose at canister.
5. Remove PCV valve from valve cover and allow valve to draw underhood air.
6. Disconnect and plug vacuum advance at the Electronic Spark Advance (ESA) unit.
7. Connect a suitable tachometer to the engine.
8. Disconnect carburetor electrical connector from the engine wiring harness, then remove the green duty cycle wire and blue idle solenoid wire from the connector. Reconnect the connector less the two wires.
9. Ground the carburetor switch using a suitable jumper wire.

Grounding Carburetor Switch:

10. Open throttle and place fast idle adjusting screw on the second highest step of fast idle cam.
11. With choke fully open, turn fast idle adjusting screw until specified fast idle RPM is obtained.
12. Return to idle, then reposition adjusting screw on the second highest step of fast idle cam to ensure speed is correct. Adjust as required.
13. Connect vacuum hoses, then remove jumper wires.
14. Disconnect carburetor electrical connector, then install green and blue wires in their correct positions. Reconnect carburetor electrical connector.
15. Install air cleaner assembly, then the PCV valve. Idle speed may change slightly. This condition is normal and engine speed should not be readjusted.