Suburban 1/2 Ton 2WD V8-454 7.4L (1987)
Idle Speed: Adjustments
Fast Idle Speed
Carbureted
Fast Idle Adjustment
Check and, if necessary, adjust ignition timing before adjusting fast idle speed. Make all adjustments with engine at normal operating temperature,
choke fully open, air cleaner installed and A/C control off, if equipped.
1.
Disconnect and plug vacuum hoses as directed on vehicle emission control label.
2.
Position fast idle screw on specified step of fast idle cam as directed on vehicle emission control label.
3.
Turn fast idle screw in or out and adjust fast idle speed to specifications.
Carburated
Check and, if necessary, adjust ignition timing before adjusting fast idle speed. Make all adjustments with engine at normal operating temperature,
choke fully open, air cleaner installed and A/C control off, if equipped.
1.
Disconnect and plug vacuum hoses as directed on vehicle emission control label.
2.
Position fast idle screw on specified step of fast idle cam as directed on vehicle emission control label.
3.
Turn fast idle screw in or out and adjust fast idle speed to specifications.
With Carburator Only
Check and, if necessary, adjust ignition timing before adjusting fast idle speed. Make all adjustments with engine at normal operating temperature,
choke fully open, air cleaner installed and A/C control off, if equipped.
1.
Disconnect and plug vacuum hoses as directed on vehicle emission control label.
2.
Position fast idle screw on specified step of fast idle cam as directed on vehicle emission control label.
3.
Turn fast idle screw in or out and adjust fast idle speed to specifications.
