1968 gts avs carburetor

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Joe1972dart

Joe1972dart

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Hello folks, recently my dad has purchased a 1968 dart gts 340 with a carter avs 4425s that when adjusting the center screw the rpms will not increase or decrease. We are curious on why nothing occurs when adjusting the screw. We have adjusted carter 2 barrels with good luck, but those have two adjustments. As far as we know the engine was rebuilt to factory specifications. If anybody can shine some light on what the problem could be it would be appreciated.
 
Joe1972dart said:
Hello folks, recently my dad has purchased a 1968 dart gts 340 with a carter avs 4425s that when adjusting the center screw the rpms will not increase or decrease. We are curious on why nothing occurs when adjusting the screw. We have adjusted carter 2 barrels with good luck, but those have two adjustments. As far as we know the engine was rebuilt to factory specifications. If anybody can shine some light on what the problem could be it would be appreciated.
Click to expand...
Do you have any picture you can share? Sometimes it helps to see whats going on.

Jake
 
The only picture I have at the moment is this one where you can see the screw at the top right corner, and the 2 block off plates where on the 2 barrel the air mixture screws would be

20191026_125630.jpg
 
The screw we are trying to adjust is the idle mixture adjusting screw that is located in the middle like pictured below

image.jpg
 
They only did the one adjusting screw in 1968 and found that it didn't work very well.
 
Nah, The idle mixture screws are recessed back in the holes below(lower than) the aluminum caps that you referenced above. The screw in the middle is just an adjustable air bleed. Shine a light in the holes in the bottom. The screws are brass and possibly frozen. Although, someone has used them because they have lead plugs over them from the factory. If yours are frozen, take it off, drain it good and blow it out with air. Your gonna add fire, so get rid of as much of the flammable stuff as possible.
Now tilt it face up on your bench, take your burnzomatic and heat the baseplate directly below the screws. Get it nice and hot like 60 seconds per screw. Now, squirt some solvent in the holes. It may smoke and evaporate at first, wait a couple seconds, then squirt again. Do this until it puddles on top of the screws. Now, try wiggling the screws (don't horse them). If they're not free, reheat and fill the holes with solvent and walk away until the next day.

DISCLAIMER: Don't use anything super flammable:D
 
Thank you guys, when the weather is better we will try adjusting to see if it helps if the screws pictured below are the correct ones. We thought that the screws under the nipples right above where the screws are actually located.

20191031_114006.jpg
 
It's not right or wrong, they control different things.
The lowest ones control the 'emulsified' fuel to the idle ports.
IIRC the single air bleed valve controls the air bled into the fuel to the transfer ports and the idle ports.
Most Carters use a second air and second idle restrictor. Would need to review the circuits on that carb before saying exactly what and where that air bleed restriction controls.

I guess the question is why you feel the need to mess with the mix screws?
Read the manuals and booklets carefully - some of those may be staked to limit their movement to far in our out. Read up on all that before forcing it.
 
We always check the carb and timing when we get cars to make sure everything is the proper way.
 
I have the same carburetor on the same engine in the same car and all my research says leave it as is. What problem are you having anyway?
 
We are not having any problems we just always make sure that everything is good when we get a new car. We are going to leave it where it is. Thank you everyone for the help.
 
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