Carter AVS question

-
azaustin

azaustin

FABO Gold Member
FABO Gold Member
Joined
Aug 9, 2016
Messages
458
Reaction score
324
Location
Lake Havasu City AZ
I have two ‘65 Darts with 235hp Charger engines. It’s been 50+ years since I worked on a Carter AVS, so I’m not an expert on them. Today I noticed that there are two holes on the front of the carb just above the butterflies that go straight through to unfiltered outside air. At first I thought that someone must have removed the plugs that should go there, so I checked the carb for my other carb. It is the same way. The car runs and idles ok, with good throttle response, the mixture screws work ok, and the idle vacuum is within specs. Is this the way this carburetor is built? Seems pretty strange to me.
 
Well we need a photo. There are no such holes that I remember

You sure you have AVS or AFB? Photos? What is the carb(s) off of originally? You can find photos and drawings of carbs in the factory shop manuals, which you can download, free, from MyMopar

Here is a 69 AVS out of the shop manual. Can you describe from this photo where these holes are?

69avs.jpg
 
Last edited:
If you are referring to the 2 dome like covers where the idle screws would go, those are set at the factory, then the plugs are put on there. Maybe someone removed them? Can you post a pic of your carb, pointing out the holes you're talking about?
 
Heres pic of my AFB from 67 273. You can see 2 sets of domes both above and below the A/F mixture screws. Ones above are smaller and angled. Not sure what they're for. Ones below I believe are the idle mix screws?

20190114_233451.jpg
 
No, this is the way they are built. I do not remember the reason why but they are built and sold with those holes open.
 
Idle mix screws are right there. 2 tubes are for PCV VALVE, and vacuum advance. Are these the two holes you're talking about?
 
Garys72Duster said:
Idle mix screws are right there. 2 tubes are for PCV VALVE, and vacuum advance. Are these the two holes you're talking about?
Click to expand...
No, re read the description. The holes are in the inside of the air filter/Venturi
 
rumblefish360 said:
No, re read the description. The holes are in the inside of the air filter/Venturi
Click to expand...
2 holes on front of the carb above the butterflies? The butterflies are inside the carb below the venturi's. Still not sure of what 2 holes you are referring to, Austin. Post a picture of a carb pointing to the holes, then they can be identified. May be an air bleed.
 
azaustin said:
Thanks to everyone for your responses. I will take a picture or two and post them later on this morning.
Click to expand...
Internal passages have to be drilled from the outside and then are plugged. Those plugs are probably made of lead and are peened with a dome shaped tool. And yes, your early A carb if original will be a AFB. The AVS had a adjustable secondary valve.
 
azaustin said:
Thanks to everyone for your responses. I will take a picture or two and post them later on this morning.
Click to expand...
That will be best. The later 60s brought changes to the idle circuit calibrations and controls.
 
This TQ has the holes inside the choke tower area like I think the OP is trying to convey. On the earlier carbs, they vent to the outside air.

358E19D2-63CB-4A18-81E9-0B005BC3B547.jpeg
 
Ok, I took some pictures and tried to upload them, but had some problems. I’m going to try again. The mounted carb is on my ‘65 Dart GT convertible with a 235hp engine. I believe it is an AFB. The other carb is the original, I think, which I found in the trunk after I bought the carb. I think is an AVS, with vacuum secondaries, since it has a second set of butterflies mounted above the throttle plates on the secondary side. The mounted carb looked pretty new. Both carbs had the holes I ‘m talking about. Thanks for everyone’s response.

07B4DC90-ECCC-4848-9411-C0A9383F1A29.jpeg


BDC59471-EAA3-4E68-B8D8-97E3339D6CD2.jpeg


B7F01943-0C7B-4CB6-9A23-7259BC016126.jpeg


DB7FA9EB-9E33-4F22-A670-8B442279A0A6.jpeg


9FD35FF6-5D13-4BBE-9797-653DA42B9111.jpeg
 
Yup, leave it alone, designed that way.
 
Holley's have them too. The way it was explained to me was, in a flooding situation i.e. stuck needle valve, they act as weep holes so the engine doesn't fill up with fuel. The hole in the TQ in post 13 are different those are for idle bypass air. Part of the smog era design.
 
Carter manual says those are to relieve vapor in the bores to assist hot starting. Only on pre-emmisions models.
http://www.imperialclub.org/Articles/AFB-AVS/Page05-reg.jpg*

There's some lists of Carter carbs by number. One posted here (FABO) as does this list at carburetor-parts.com says 3644 was for 1964 413 CID engines.
Look in the '65 Shop Manual to see what AFB was used on the 273s that year.

Your other carb has an idle air bleed screw (needle valve) in addition to the idle fuel mix screws. Originally those were used on cars equiped with two AFBs but maybe were used on other applications later on. The New AFB Carburetor (Session 121) Master Technician's Service Conference p.21

*page 5 from Carter AFB-AVS Service Manual
 
Thanks for the links. I was curious about the needle valve. That carb was stamped 3854S, followed by D5. Interesting that the bleeds vent to unfiltered air. It was a different world then.

Thanks again to everyone for all the responses and information.
 
Dana said:
Holley's have them too. The way it was explained to me was, in a flooding situation i.e. stuck needle valve, they act as weep holes so the engine doesn't fill up with fuel. The hole in the TQ in post 13 are different those are for idle bypass air. Part of the smog era design.
Click to expand...

So, gas is supposed to take a 90 degree turn and flow out those holes instead of going straight down the carburetor's barrels? Seriously you don't believe that.
 
It will but it in liquid form. When the carb gets loaded with vapor, it will exit. Apon starting, air will go in that hole to help clear out the vapor.
 
RustyRatRod said:
So, gas is supposed to take a 90 degree turn and flow out those holes instead of going straight down the carburetor's barrels? Seriously you don't believe that.
Click to expand...
When you put one together and the needle has a speck dirt in it, and gas is pouring out of the boosters, with the throttle blades completely shut, I've watched it happen. So, yes. Although like I said, Mattax's explanation makes more sense from the design aspect.
 
Dana said:
When you put one together and the needle has a speck dirt in it, and gas is pouring out of the boosters, with the throttle blades completely shut, I've watched it happen. So, yes. Although like I said, Mattax's explanation makes more sense from the design aspect.
Click to expand...

I wasn't trying to be a smartass......even though that's how it appeared......but I would have to see it to believe it.
 
You must log in or register to reply here.
-

Back
Top