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Old 03-04-2009, 11:50 AM   #1
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Motorcraft 2100 carb help

I am in the process of a carb swap from the Carter to a MC2100, after installing the MC2100 it fired right up and the weather was in the low 30's outside, way better than what the Carter would do. At first I had a vacuum leak and couldn't get the idle down. I corrected the plate/carb stack-up with fresh homemade gaskets, now it would idle down to about 800 or so but idling rough. I found a leak in the choke diaphragm set-up which I then plugged, it was idling better but not great. I have an HEI ignition set-up and have yet to throw a timing light on it. I will update the post with that info once I adjust the float height and replace the Power valve. It needs some tweaking before its trail or road ready, a few questions for the experts...

1. During the tuning process I had a backfire through the carb and blew out my power valve, a 8.5 hg was included with my rebuild kit, should I replace that one or go slightly lower? I know there is a calculation I've run across out there but I have yet to hook a vacuum gage to it while it's running. I installed a spectra power valve saver to prevent this in the future.
2. What do you guys suggest for the float height from the top of the flange? Right now i have it set "dry" to about 1/4".
3. For the short while I had it running it seems to be really rich, my current jets are 49s I plan to pick-up some 46s or 47s, does that sound about right?
4. I have a manual choke kit for it that I plan to swap in, is there a hole under the base plate of the carb I need to plug? Is it also safe to remove the choke pull down diaphragm if I am going with a manual set-up?
5. I checked my fuel pressure going into the carb, the stock pump has it about 7psi. Is this too much? I've read the MC2100s like 4-5psi, should a regulator be installed to lower the pressure?

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Old 03-09-2009, 07:51 AM   #2
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Anyone?

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Old 03-12-2009, 03:29 PM   #3
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Quote:
Originally Posted by zilla24 View Post
I am in the process of a carb swap from the Carter to a MC2100, after installing the MC2100 it fired right up and the weather was in the low 30's outside, way better than what the Carter would do. At first I had a vacuum leak and couldn't get the idle down. I corrected the plate/carb stack-up with fresh homemade gaskets, now it would idle down to about 800 or so but idling rough. I found a leak in the choke diaphragm set-up which I then plugged, it was idling better but not great. I have an HEI ignition set-up and have yet to throw a timing light on it. I will update the post with that info once I adjust the float height and replace the Power valve. It needs some tweaking before its trail or road ready, a few questions for the experts...

1. During the tuning process I had a backfire through the carb and blew out my power valve, a 8.5 hg was included with my rebuild kit, should I replace that one or go slightly lower? I know there is a calculation I've run across out there but I have yet to hook a vacuum gage to it while it's running. I installed a spectra power valve saver to prevent this in the future.

Yes, replace it.

2. What do you guys suggest for the float height from the top of the flange? Right now i have it set "dry" to about 1/4".

I dont measure float heights in inches, or at all. I usually start so the float is level in the bowl, adjust as necessary.

3. For the short while I had it running it seems to be really rich, my current jets are 49s I plan to pick-up some 46s or 47s, does that sound about right?

not sure on that

4. I have a manual choke kit for it that I plan to swap in, is there a hole under the base plate of the carb I need to plug? Is it also safe to remove the choke pull down diaphragm if I am going with a manual set-up?

Dont know about a hole on that carb, remove the ugly ass dia fragm.

5. I checked my fuel pressure going into the carb, the stock pump has it about 7psi. Is this too much? I've read the MC2100s like 4-5psi, should a regulator be installed to lower the pressure?
get a regulator and set it to 5 psi, adjust from there.

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Old 03-12-2009, 03:32 PM   #4
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why dont you wanna use the electric choke?
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Old 03-13-2009, 05:36 AM   #5
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I was planning on going manual choke for simplicity and the fact the electric choke is not working. It is hooked to a 12v power source but does not open as the engine warms up.

I just ordered some #47 jets and a few float, I plan to mess around with the jeep some tomorrow. I haven't bought a regulator yet, from what I can see some people run them and others don't. I guess I'll try again without it and see if I can dial it in before I run out and buy one.
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Old 03-04-2010, 12:18 PM   #6
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I have a 2100 on a 89 with 4.2L I do not have a regulator. About the jetting no idea I bought mine from some guy on ebay, installed and some fuel adjustments and its running fine. good luck
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Old 03-05-2010, 10:13 PM   #7
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what altitude are you at or just tell me where you live and i can tell you what jet to buy.
and if you did not use a heat spacer gasket that can be a problem.
and is your 2100 a 108 or a 121 ( it should be stamped on the side of the carb.)
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Old 07-16-2011, 12:37 AM   #8
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sorry to revamp an old thread but I'm interested in how this all turned out. I just installed my motorcraft carb and whereas it ran good for a few weeks I'm having trouble with idle now. wants to bog down when load is applied, and sometimes I am forced to shift to neutral (automatic) when stopping. any help?

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