I have a '69 AVS, 4618S, and am wondering about a few things. This plug is supposed to cover an off idle adjustment screw, according to the FSM. Should I gain access to it for cleaning and adjustment?



There is a spring inside that presses against a ball bearing, and on the top, it opens to the atmosphere.



It allows extra air to enter after the idle mixture screw, which itself just adjusts how much the idle fuel is diluted.



This is where the air comes from that goes through the idle mixture screw, and into the idle circuit.



This is where the idle limiter screws, as the FSM calls them, are located. They are covered by a plug and staked in. Should I gain access to them for the rebuild also?



Finally, there is this thermostatic air bleed, which I thought was only on A/C equipped cars, like the 4640S carb. It looks like it opens to a blind hole. I don't see any holes inside. Wonder why they wouldn't eliminate it on carbs that aren't drilled for it.





Why are the Edelbrock mixture screws up on the diagonal part, and the Carter has the same plugs next to the PCV port, and their mixture screws are below those?

My AVS carbs are the slightly later 2 screw design but the info below may be of some help.

http://www.forabodiesonly.com/mopar/showthread.php?t=50847

http://www.forabodiesonly.com/mopar/showthread.php?t=29582

and here's a link to how I converted my Carter AVS to annular boosters

http://www.mymopar.com/forums/index.php?showtopic=9065

On your bottom photo where the tip pf your pencil is pointing , those WERE the idle mixture screws , they are broken off because the steel screw is frozen in the cast alum body .

maybe, but not necessarily. Can't quite see. Those were emissions carbs, and on a virgin carb, there was a lead plug over the mixture screws. The screw head was recessed deep into the carb below the plug. An early attempt to prevent owner tampering.

Two of the biggest problems I have found with Carter AVS carbs is vacuum leaks & poor parts availability.

Look for wear on stepup pistons, rods, the primary jets are most likely oversize/oval, the throttle shafts especially the primary is most likely worn & mayme the body of the carb. The hot air compensator valve needs checked as the bimetal strips fail, is this the valve that you think goes to a blind hole? it usually is open to the botton of the carb.

Only buy good quality rebuild/gasket kits, I have had trouble with sub standard gasket material failing with modern gas & the thick insulating base gaskets in some of the cheap repo kits are not worth a pinch of sh!t.

If you find a source for spare parts (other than rebuild/gasket kits) at a reasonable price please let me know.

Actually,the casting has provisions for mixture screws in both locations depending on year and application.If not used they are plugged.Here is a 70 4spd I recently finished.Note location.I have taken a lot of carbs with the one screw,which incidently is a left hand thread and eliminated it and went with two screws in the base.Much easier to tune.Also,on the carbs with one mixture screw,you will find pre-adjusted mixture screws behind the plugs in the base due to emission requirements.

Here's one of the early style

This is an interesting thread.

Thank you.

I love my Carters!

interesting indeed

I fixed the pics I messed up on showing the thermostatic valve.

This is very interesting I have 3 69 383 4bbl carbs and they all have mixture screws where those supposed plugs are ?

I did have a 68 carb that had to one up top, but I can't remember if it also had the screws at the bottom also ?

John your 69's are typical, the early 68 AVS carbs had the single adjuster, most later 68's had two adjusters as your 69's do. I have also seen some 69's with the single adjuster, not really sure why they came both ways.

I think the 4618S had the single air bleed screw up top, and the 4618SA eliminated it, and added conventional adjusting screws where the idle limiter screws were in the earlier series. Perhaps it didn't accomplish it's goal, like the carbs were too lean, and getting lean misfires at idle, thus defeating the purpose of the leaner, reduced adjustability design.

The "SA" carbs were replacement carbs and would have had the later style adjusters.

Ever see one with all 3?

Hey 375inStroke can you post a photo of the base of your carb please, I'd like to see the underside.

I can't find any single screw carb bodies & this 2 screw one is dirty but you will get the drift. The port the pencil is in goes all the way through from the hot idle compensator valve to the base of the carb on all the carbs I have, some of them have a vacuum port low on the carb that comes off this port for the flaps in the airfilter snorkels.

I'll post a pic later. There is a passage in the bottom like your carb, but it doesn't go all the way through. On top, where the valve is, the port goes down about 3/8", and stops. There isn't a plug or anything. It is the casting itself.

Cheers, like I say all mine have the port all the way through & they are all different models, some 625cfm 383 some 625cfm 440 & some 750cfm 440 carbs but all of mine have 2 idle mixture screws. I will check through some other info I have & post again later tonight (NZ time)

The FSM says the thermostatic valve is for A/C equipped cars. Are any of those carbs for non-A/C equipped engines?

My 68 SM says the top screw is a off idle adjustment and the two screws under the plugs are factory set, maybe its a 4-speed thing. BTW the carb in the pic is a 69 but notice the dashpot for the 4-speed cars.