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1966 Mustang, 289, 4 speed, positive traction rear end
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4100 1.08 carbs are getting harder and harder to find. Has anyone looked into reproducing one or two 4100 carbs, on cnc machine. Does anyone have the schematics or drawings of our 4100 carbs for 289's? This is something I was thinking about, dont know if it could be done or not.
 

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Not cost effective. I replaced a 4100 and put a $350 quick fuel slayer carb on my car. It’s superior in every way to the 4100.
 

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Wouldn't be cost-effective to do one or two. But it might be cost-effective to do a couple thousand for those people looking for the closest thing possible to an original that has done a tremendous job for going on sixty years now... And I don't have anywhere near $350 and to all of my 4100s combined.
 

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I would be happy if someone would just reproduce the primary throttle shaft for the 2100 and 4100. I have two that are worn.
 

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The 1.08" Autolite is 470CFM. Not much use for anything except gas mileage. Maybe enough carburetor for a hot 221" Fairlane V8 or a 260 perhaps if you used two of them.

You won't see any reproduced in your lifetime. No reason.
 

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I thought the body would wear before the shaft as well but I have two carbs on my bench with worn shafts but good bodies. One of the carbs has significant wear on the shaft with little wear on the carb body. I bought a reamer and bushings to rebush the carb body but probably won’t now given how tight the reamer shaft fonts in the body.
 

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It is possible to create new die-cast tooling to repop the carb bodies, but to do that in China would be probably $10+ grand for the main housing, even as a “prototype”, low production volume tool. Then you have to finish machine it and install the other parts into the housing.

But I agree with the others in that there really isn’t a market out there with any reasonable production volumes out there that could ever pay back the tool, unfortunately.
 

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It is possible to create new die-cast tooling to repop the carb bodies, but to do that in China would be probably $10+ grand for the main housing, even as a “prototype”, low production volume tool. Then you have to finish machine it and install the other parts into the housing.

But I agree with the others in that there really isn’t a market out there with any reasonable production volumes out there that could ever pay back the tool, unfortunately.
Uhm... isn’t the summit carb exactly what you’re talking about?
 

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The Summit/old Holley 4010? Do they still make that? I thought that was an “improved” 4100? I could be wrong.

My thought above would be what it would take do do an exact copy 4100 repop. While cool to do, it doesn’t make good business sense. I know I don’t have spare cash laying around to build the tooling...
 

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I would be happy if someone would just reproduce the primary throttle shaft for the 2100 and 4100. I have two that are worn.
you can probably get bushing inserts to fix that. I have a couple parts carbs, I am sure others do too. It’s hound the be too hard to find a throttle shaft. How did you know yours were bad?
 

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it is very obvious that two of my throttle shafts were worn when I removed them from the carb per visual inspection and by feeling the worn groves in the shafts where the shaft rides in the carb body.

I have a third carb with very little wear but the wrong linkage on the shaft that is not worn; that shaft in the two other carb bodies is snug. I may cut the linkage off that shaft and weld the proper linkage back on.

So for my three carbs, I have two worn shafts and zero worn carb bodies. BTW, I also bought bushing and a reamer kit, but it turns out I will not need them.

I am still looking for a source of throttle shafts as some carb rebuilder must have a source. I may reach out to a machinist and have a few made.
 

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Post a pic of the worn ones. Someone here may have a spare
 

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A 3 D printer could make them.
 

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761921


I am looking for a 4100 primary throttle shaft like the one here. Some 2100 shafts are the same. Anyone have a good one ore a source for new ones? I mention this before, but I have a couple Autolite with worn shafts but good throttle shaft bores (this carb included). I have another really good shaft, but the linkage is not correct.
 
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