On an engine build I'm going to end up using an Edelbrock #7116 intake for Vortec heads. It has the square carb flange. Normally I run Qjets but hood clearance will not allow me to make that happen. I've always been an AFB fan, I have a couple AVS's as well from 70-71 Mopars. I would like to convert one of them to electric choke and run it. I haven't done a ton of research on it yet, but I see a couple issues. The first is that the front bosses where it seems the new choke in the conversion kit has to screw on are not drilled or tapped on either carb. I could take care of that myself. The other thing is the vacuum input to the new choke. Both carbs have a brass barb in the spot where an o-ring seals the new choke housing. I'm guessing I can work that fitting out and then put the o-ring there? If anybody has tried this I would appreciate some input. I'm not going to make the mistake of getting into the leather accelerator pump debate again. My question is for those of you who are running the leather pumps, where are you getting them? Thanks in advance.
dang....they did have them and had one on a car I bought.......maybe I can find it as I took it off.....
Will the electric choke conversion even need the vacuum source or is there a choke pull-off built into it?
The conversion kits are for performer carbs, but I’ve seen them used on older AFBs. They seem to use the vacuum port with an o-ring. The choke housing would go in place of the pull off on the AVS carbs I have. The kits come with a linkage rod for the choke shaft, but I’m not sure it would work, although it seems the dimensions of AFBs and AVSs seems to be the same. I guess worst case scenario I order the kit and if it doesn’t work on the AVS I convert one of my AFBs. I’m hoping someone who has done the conversion will weigh in.
The vacuum input to the choke housing was a pressed-in bushing with an orifice to control the vacuum. The orifice size varied with different applications. The orifice diameter is important. Do not remember ever seeing an AVS with integral choke. The 1966 Chevrolet, and I believe all of the MoPar versions used a divorced choke. The leather accelerator pumps are contained in carburetor rebuilding kits produced by The Carburetor Shop. EDIT: after re-reading my answer, it occurs to me the next question is going to be the size of the orifice. And I don't know, as this will be a non-standard installation. The barbed tube has a significantly larger I.D. than the orifice for the integral choke, and provided a vacuum source to the external choke pull-off. The external choke pull-offs had a variable orifice depending on application. I suppose if I were doing this conversion, I would find a dead choke pull-off for the exact application, carefully disassemble, and measure the orifice. I believe that would be a good starting point. Jon.
Thanks, Jon.The only Carters I've run were manual choke AFBs, so I'm a little behind the knowledge curve here. Most of my experience is with quadrajets. I found a close up of the back of the choke housing, there is a recess there for the o-ring apparently. And the person doing the conversion who posted the photo pried out a lead plug and found an orifice behind that. Even cutting off the barb on my carbs would leave a larger opening than that I believe. I did not know size mattered in this case because I'm still a little hazy on how it works. I read something that said the vacuum is supplied just to make sure the choke is held open when the engine is warm, but it would make sense that you would have to have something functioning as a pull-off. The pull off I have has a very tiny orifice on the inlet that gets it's vacuum from the barb in question. I don't know if it has something else internal other than the diaphram. I know on qjets we could drill little pieces of plastic with various sizes to use on the various pull-offs, but that would not work here since the housing is right against the opening with no rubber line. Yes, I know I could drop about $500 or so for a "Thunder AVS," but where's the fun in that?
On Carter AFB's with integral chokes, a small brass bushing, or plug if you wish, was pressed into the same hole where the barbed fitting is on your AVS. The bushing/plug had an orifice drilled through the middle. The "O-ring" is actually a flat rubber gasket, not an O-ring. Jon.
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