Holley List1850 carb help
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Freshman User
Joined: Jun 2009
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From: Ozark, AR
Holley List1850 carb help
Hey everyone, I'm back with yet another puzzle. First off, I am now in the process of tuning my carb and there in lies the problem. I can't get it to idle down below 2000 rpm's. I have no vacuum issues, everything is sealed. The idle adjustment screw on the linkage side is turned out completely off of the shaft so it has no effect on it. However, I can pull on the linkage and it will idle down till the engine just stalls cause of low of idle. If I hold the linkage just right it will purr like a kitten at around 800 rpm's. There is plenty of slack in the throttle cable for propper allowence, no binding or stretching. I did buy the carb used and I have reason to believe that the secondary adjustment screw, located under the butterfly plate, may have been messed with before I got it. If this is the case, then what would the propper adjustment be? The Holley Carb Tuning DVD is not much help but, it is great for the idle vacuum adjustments. I just need a little more info on it before I start ripping all back apart again. I'm open to any and all suggestions. Thanks.
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Freshman User
Joined: Jun 2009
Posts: 43
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From: Ozark, AR
Ok, I believe I have found the problem. The fast idle adjust screw was turned all the way in and wouldn't let the mains seat when the choke was heated and opened. I did check the secondary idle setting and readjusted it. Before I adjusted it, the main circuits where exposed as much as a pen head. From my research, of all that I could find, this is way too much opening for my application. I turned the adjustment screw until the butterfly completely seated without further movement. Then, I started to turn the screw back in just til I saw the butterfly start to move then at this point I opened it up one full turn and the butterfly is now resting at the very bottom edge of the main circuit. Would this be a good adjustment to work with or would I have to close it more? After I have this set I will be able to mount the carb and readjust the fast idle screw. Oh, by the way I am running a 302 with a 600cfm Holley carb atop of a Weiand stealth intake, a mild cam duration @ .050 int.:194, exh:204 or something very close to those numbers but I cant remember the lift and BBK headers leading into 2.5 inch exhaust. The heads have been cleaned and refreshed with new valve seals. Thanks.
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Joined: Jan 2001
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From: Virginia
I know it's kind of hard to see, but I have read that when the secondary stop is right, and the idle adjustment is correct, when you take the carb off and look underneath at the slot in the primaries, the slot should look close to being a square. In other words, the primary butterflies should cover enough of the slot to make it look square. If it gets off too much, you may have a off-idle or "tip in" stumble. The slot is the "transition" slot, and adds more fuel on top of the idle circuit, and before the mains kick in.
