These are very simple carbs to work on but actual tuning is made difficult by the lack of tuning parts available for them. The Edelbrock carbs are very similar & use the same parts for tuning though
Step1 - Check the float level , this requires removal of the top of the carb , once removed invert the top & use a drill bit to check the distance between the top of the float at the end away from the pivot & the body with the gasket in place , Most AFB & AVS Carbs use a 7/32 float setting, the 383 avs seem to use 5/16 instead , with the EDDYS there should be a spec in the manual with the carb > this should be checked even with new carbs as they can bend during shipping , bend the tab that touches the bootm of needle to adjust the settings. While you have the top off also set the float drop , this is the measurement from the top of the float to the body when the top is the right way up , there is a tab behind the needle that can be bent to adjust the drop , the spec for drop is 1/2".
Step 2 - reassemble the carb get the engine running & warm , make sure the dist vacuum hose is connected to the port 1/3of the way up the carb on the right side of the front of the carb ,adjust the mixture screws & get the car running as good as possible now take a manifold vacuum reading, at idle , in gear if it is an automatic tranny, [you can remove the cap above the metering rod & watch to see if the rod stays in the down position at idle ] there is a spring under the metering rod which will need to be changed if the rods do not stay down at idle , springs are available in 3,4,5,7or8" increments & you need to uise a spring at least 1" below the vacuum reading you get.
Step 3 - adjust the jetting, take the car for a drive at a steady cruise & resonable speed 30 mph + for 5-10 miles & using a new spark plug check the color you want tan -orange color if it is Chocolate or darker you want to down jet, if it is light orange to white you need to upjet . This not as easy as it seems , you need to remove the top of the carb & change both the jets & metering rods to move one step at a time , you will need the chart & the tuning kit part#1480 [Hopefully someone can scan the chart for us , hint hint] I have commonly found the Eddy carbs to run lean even with the biggest available jets installed , you may need to drill them with # bits to get enough flow I have also modified & made metering rods to try to get both steps correct [up position & down position]
Step 4 - Floor the car a dead stop upto the speed limit shut off & check the plug color again if it is darker or lighter adjust the rear jets the same way as the front jets
Step 5 - adjust the accelerater pump arm , by adjusting the rod away from the body you decrease the amount of fuel delivered , you want as little fuel delivered as possible without creating a bog. if it bogs immediatly move closer to the body again, there are only 2 holes or sometimes 3 depending on the model of carb you have so you cannot adjust it much.
If it bogs 1/2 a second after the throttle is floored you will need a larger squirter which can be a problem I have not been able to get new ones of different sizes but you can drill them with # drills & if you go too big you will need to solder the tube & redrill. You wil have to remove the top of the carb to get at the squirter
Step 6 - for maximum performance you need to adjust the rear air door ,on the AVS this is esay , you can undo the outer lock screw & adjust the center screw 1/4 turna at a time counterclockwise until you can feel the secondaries bog as the air door opens then tighten the screw 1/4 turns until no bog can be felt. With the AFB this is much more difficult, you need to remove the top of the carb again & remove the rear boosters & remove the air door , at the bottom of the weights you need to drill 2 holes [1 each side] & try the carb out if no bog is felt you can make a second hole 1 side at a time , or enlarge the first hole now you can either play chicken & say to yourself , it is better I quit or keep going until a bog is felt , at which point you either need to weld a hole back in or tap the hole & put a screw in to add weight again , my experience is that you can drill 2 3/16" holes in virtually any application & not bog after that it will depend how much converter & gear etc you have as to how much more can safely be removed