I recently purchased a remanufactured Motorcraft carb from Summit. The carb apparently has a terminal for an electric choke, however last I recall the truck I'm working on doesn't have an electric choke setup. I don't know a thing when it comes to the choke on carbs. If I remember correctly, the carb I removed with a manual choke had similar looking choke parts on it. Is there a chance this carb will work?

 

Should work fine. Find a 12V source for power and run a 12 gauge wire to the choke coil.
It grounds thru the carb. The black cap that you plug the wire onto is adjustable. Loosen the 3 screws and turn the cap. Should be marks on it for richer or leaner. See how the choke works first and adjust if needed.

 

DO NOT QUOTE ME ON THIS...

But I believe that electric choke connects to one of the terminals on the back of the alternator, and gets something like 7v when the engine is running. It might be the "I" terminal but its been too long since I've played with one. Adjustment is pretty simple. There should be a set of notches on the housing and a single notch on the black plastic choke cap. Set it 2 notches "rich" from the big notch in the center of the housing and try that to start. Its hard to see in this pic, but you can see the notch in the choke cap lined up with the big center notch on the carb housing:



Hopefully someone else can chime in here and clarify this... I feel like I'm not explaining it very well

This guy also has some good info: http://www.gottafishcarburetors.com/...tallation.html

 

Sorry, quoting you anyway

The factory electric choke is powered from the stator terminal (marked S or STA) of the alternator. It's not actually 7 volts, it just "looks" like it's 7 volts using a handheld meter. It's actually a three-phase AC signal that's all over the place.

 

FMC400: One of your posts is where I got the electric choke connection info, how do you like that?

I need to figure out how to plumb my hot air choke now that I have headers. I was thinking about wrapping a coil of steel tube around one of the primaries, and feed it into the port in the bottom of the choke. Other end would hook to the nipple on the air cleaner. I also need to figure out how I'm going to hook up the electric portion now that I have a 3G alternator, I'm not sure the stator terminal has the same type of output at the same voltage.

 

Wouldn't have been me. Here's my write-up on chokes, explaining how the choke is connected to the stator (near the bottom):

https://www.ford-trucks.com/forums/8...ml#post6939116

I have wondered about this as well; it would be helpful to measure the signal level with both setups using a true-RMS meter. The concept of the stator between the two alternators is the exact same, so I would be surprised if the difference was meaningful. I assume you're using the original carburetor?

 

Not sure if my Fluke DMM can do anything useful with that input, but I have a friend with an O-Scope who loves fiddling with stuff. When I get the truck up and running again, I'll be sure to take a look.

My 4100 is not a truck carb, its a C3AF-R 1.12" bore, so 600cfm vacuum secondary with auto trans linkage. Come to think about it, I know it has the hot air hookup, but I'm not sure about the electric. I've got 6 squarebore cabs sitting on the workbench in the garage right now so I'll have to check this evening. I believe its originally for a 390FE powered Ford or Mercury sedan, jets are something like 54 or 57F & 62 or 65R, but it uses standard Holley jets so I'm not going to stress about it as it should be pretty close to start. I have a wideband o2 sensor for tuning so that should be cake. I've been trying to find a really good rebuild kit for my 4100, but have not found anything I like yet.

On a related note, can you use Holley vacuum secondary springs for tuning a 4100?

 

I ran my trucks choke from a 3g alternators stator teeminal before I finally switched to tbi injection. Just spiced into the wire that loops from the regulator to the single terminal. Worked as good as the 1g alt did.

 

You can easily run a wire to the choke for the new carb, or transfer your manual choke from the old carb and put it on the new one.

 

Good to hear from someone who has actually done it! I may have to give it a try
I think the old 2100 used hot air + heater hose held in a bracket against the cap to keep the choke warm. I wonder if that bracket and choke cap will swap between the 2100 and the 4100? Something to try at any rate.

JReagan90: Sorry for the thread hijack, hopefully some of it was useful!