carter AVS mixture screws ?

[rustymetal]

I just bought a used AVS date coded carb for my 68 dodge, and where the mixture screws should be it looks like there is lead in the holes. I dont see any needles sticking out of the inside of the holes in the throat of the carb. Has anybody else ever seen this? shoudnt there be mixture screws in these holes? Hopefully I didnt get screwed. HAHA any throughts would be great rustymetal

 

[rumblefish360]

On some years, the idle mixtures screws were not installed or had caps on them to prevent Tom, Dick and Harry from fooling around with them so the car stays in tune and emissions compliant. Your AVS has come with plugs where the mixture screws were to be. Later years (TQ era) had caps.

(IIRC)

 

[rustymetal]

Hey thanks for the reply. Shoud I try to take the plugs out so I can put screws in them? where would I find the right mixture screws for the carb? rustymetal

 

[62MAX]

If the bottom has plugs,you should still have one in the center at the top of the body.There are screws behind the plug's that are pre-set
,originally intended to be non adjustable by the owner for emission purpose's .Most were removed over the years and screws installed

 

[bbeep69]

Yes, there should be mixture screws visible - unless you somehow have run across a carb that was installed on a California car. Emissions in California have always been more stringent and I suspect that this is why your carb has no idle mixture screws. The California Clean Air Board did not want the carbs being messed with so I suspect that the idle mixture was made impossible to adjust. I'm speculating here but it makes sense if your carb has plugs in place where idle mixture screws should be.

 

[Meep-Meep]

Yes, the late 60's carbs typically had the single mixture screw on top.

Another thing to note on these factory AVS carbs is the cast boss in the lid above the single mixture screw. Inside under the plug is a valve, a spring and an adjustment screw that is also non user adjustable. I believe that screw sets the tension of the spring so that the valve opens at the right time based on the vacuum signal in the transfer slot (I'm sure it's calibrated to open at a certain vacuum level kind of like a Holley power valve) and that allows air into the idle circuit through the small hole on the side of that boss as you tip in. The purpose must be to correct the off idle mixture for emission purposes, or lean it out under deceleration where vacuum is very high in that circuit, and I bet this little gizmo could be one of the reasons that the 60's MoPars never had air pumps like GM and Ford. Yet one more reason to go with MoPar!!!

With all that said the carb is now 40 yrs older so you need to look on the gasket side of the lid, through the hole, and see if that valve is free to move and isn't filled up with rust and corrosion. If it's stuck open it's possible you could end up with an incurable weak mixture similar to a vacuum leak.