Holley 4160 Help!!!

[75CherokeeS]

I have a holley that will not drop in idle. I think I need help adjusting the fast idle. Does anyone know a how to set that screw? Any insight on why my carb would idle way too high would be appreciated.

[AMX factor]

If the idle isn't dropping you might have a vacuum leak. Holley throttle plates are notorius for being warped and a hard seal around the base to the intake.

[1979 wagoneer]

TURN FAST IDLE SCREW ALLTHE WAY IN,BACK OFF
1 1/4 TURN

[Obi-Wan]

1979 wagoneer, are you sure you're talking about the fast idle screw (which controls the idle speed when the choke is engaged)? Your 1.25 turn statement sounds like an initial setting for the idle mixture screws (which control fuel:air mixture at idle speed).

75CherokeeS, the first thing I'd try is adjusting the idle mixture screws correctly and see if that helps. These are the small screws in either side of the front metering block. As mentioned, a reasonable initial setting is about 1.5 turns out. Be sure to set them both the same.

Then turn your normal idle speed screw (on the main throttle linkage) outward until the bottom is no longer touching.

The fast idle screw is on the passenger side of the carb near the choke linkage. Yours is probably located differently than my manual choke is. Turn that out until it's no longer bottoming, either.

With these three changes, your idle speed should drop to around 500-600 rpm.

Now fine tune your idle mixture screws by turning them both in 1/4 turn at a time, alternating from one side to the other. When you hear a noticeable drop in idle speed/quality, turn the screw back out 1/8 turn and leave it there. Now continue turning the other screw inward until it also affects the idle, then back it off 1/8 turn. You've now set your carb to "best lean idle."

Now turn your primary idle speed screw inward until your idle climbs to 600-700 rpm with the tranny in drive (add about 200 rpm if in park). The TSM says 600 is recommended, but my 401 idles considerably better at 700 rpm, so I set it there.

I forget what the proper setting is for the fast idle speed -- probably around 1000 or so in drive.

[SAustinwag]

Step 1) get rid of 4160 carb smile.gif