Hot Rod Forum : Hotrodders Bulletin Board

Hot Rod Forum : Hotrodders Bulletin Board (
-   Engine (
-   -   Carter AFB carburetor question (

421Bonneville 08-03-2004 02:15 PM

Carter AFB carburetor question
One of the many different versions of the AFB 4 barrel has a large screw between the two small mixture adjustment screws in the bottom front of the carb. What the heck is this? Can't find a reference to it in Chilton, Motors, etc.

machine shop tom 08-03-2004 03:00 PM

That's the idle air adjustment screw, used on some Pontiac, Cadillac, Chrysler, and Linclon models. It is used to adjust idle speed. With the engine at normal operating temp, turn the idle air screw outward to increase engine speed. This will lean the engine out which must be compensated by re-adjusting the idle mixture screws.

(info from 1969 Motors manual)


Pony 08-03-2004 03:06 PM

Found it in a 1973 Motors Manual in the Carter carb section. Says that type of carb was used on Pontiac and Lincoln. It's an Idle Air Screw. States that this carb doesn't have the usual idle speed screw and uses this for that function. You turn the screw outward to increase idle speed, this leans out the idle circuit and the two idle mixture need to be adjusted at the same time to get the idle speed and mixture correct.:thumbup:

ps. Looks like Tom and I found it at the same time:D

machine shop tom 08-03-2004 03:14 PM

Great minds think alike! (And look up stuff at the same time, also!)


421Bonneville 08-03-2004 04:40 PM

To the great minds, thanks from those of us with less than great minds. Frank:rolleyes:

All times are GMT -6. The time now is 12:44 AM.

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright 1999 - 2012. All Rights Reserved.