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apeters89 04-07-2003 02:31 PM

Motorcraft 2100
After a day of wheeling I REALLY need to get rid of my fawking Carter carb. I was looking for information on the Motorcraft 2100, and everyone says it's great for the 258. I just need to know what years and what model vehicles they came in because the stupid people at the parts store don't know how to look it up. I tried the search, but can't get any definite year/model info to work with.



BostonWrangler 04-07-2003 02:40 PM

Try any late 1970s to 1980s Wagoneer/Grand Wagoneer with 360. If you get an earlier carb, it won't have the annoying altitude adjustment crap on the back of the carb.

The hardest part of the swap isn't even hard. You need to fabricate a small linkage adapter for the throttle. The 2100 is designed to have the throttle cable pull BACKWARDS, but the 258 throttle cable/rod pulls DOWNWARDS. All you need is a piece of 1"x3" thin metal, a drill and a couple bolts. You could even just weld the sucker on.

Here is some info I compile a while ago.

Rebuild kits:
2100: Napa (Echlin brand) 2-5585approx $12+ tax.

Sorensen from AutoZone about $21 + tax.

BBD: Napa (Echlin) 2-5671C approx $15 + tax.

Bolt patterns(as measured center of hole to center of hole):

BBD = 3 1/4 x 1 7/8 inches 4 bolt 2 bbl
2100 = 5 1/8 x 4 1/2 inches 4 bolt 2 bbl

The Mr Gasket part number is 1937, which is a standard 2 BBL to 4 BBL adapter. The 2100 has a 4 BBL bolt pattern.

The cfm rating for the M/C 2100 depends on the model that you have. Look for the following numbe sequence in the model number:

1.08 = 200 cfm
1.14 = 200 to 300 cfm
1.21 = 360 cfm

Engines to get a 2100 from to name a few:

AMC 304, 360
Ford 302, 330, 350, 360, 351, 390, 400, 429.

Look for Ford/Mercury vehicles from the 70s: Bronco, Comet, Cougar, Maverick, Meteor, Montego, F-250, Econoline, Falcon, Fairlane, Mustang, Torino.

drewmandrews 04-07-2003 08:33 PM

Also 1969 Fords. I reccomend the 1.08. The year number is stamped on the bottom in relief form, in other words it'll say 69, 70, 71, etc. On the side will be the cfm 1.08, 1.21, etc. 1.08 is the most fuel efficient, higher than that wastes gas. I have 2 and like them both. Bolted on 258 6cyls. Good execution uphills and down without stuttering or sputtering. Easy to rebuild. K&N filter assembly fits nicely on it too if your local allows it.

Comet 04-07-2003 08:40 PM

I'd be surprised if the auto parts store carries the Motorcraft. None did around where I live anyway. I mail ordered one out of a co. in AZ, I think $168 exchange. Don't know what the core charge was though.

big bad Jeepster 04-07-2003 09:02 PM

They are a great carb! I run the 1.08 on my 225 V6. $30 from a wrecker and $20 for a rebuild kit. Much cheaper then buying a new/rebuilt one.

drewmandrews 04-07-2003 09:29 PM

Yeah, after talking to many "carb" sellers, I went to jeep yard and got one off an early model CJ. $20.00 + paid $60.00 for rebuild and another $40.00 for electric choke, which I reccomend.

CJ5-Man 04-07-2003 09:50 PM

Every yard I've been to every motorcraft carb has been taken.

Give yourself all day to find one, cause its a popular carb for lots of stuff like dirt track and racing where you have to have a 2 barrel to comply with rules.

Rockcrusher 04-07-2003 09:59 PM


Originally posted by big bad Jeepster
They are a great carb! I run the 1.08 on my 225 V6. $30 from a wrecker and $20 for a rebuild kit. Much cheaper then buying a new/rebuilt one.
Where did you get the adapter plate to mount the 2100 on your manifold?

apeters89 04-07-2003 11:01 PM

ordered one from Autozone (for a 1978 AMC AMX w/ 304 V8) of all places... $160. I haven't had a lot of free time to work on my Jeep (putting tile in the house, myself) so I didn't want to bother with the rebuild. As soon as it comes in I'll figure out what adapter I need, and how to fix the throttle linkage.

Thanks for the info.

big bad Jeepster 04-07-2003 11:10 PM

Seems how I have an offy 4bb intake, I bought an adapter from kragen for $20. The screws they suppy are junk so upgrading to allens would be a good idea. You can get more of a torque to seal the carb on the manifold.
Rebuilding isnt hard at all. I rebuilt one up at winter fun fest on the fender of my trailer at midnight. Only took me 15 min.

drewmandrews 04-07-2003 11:25 PM

Yep, BostonWrangler gives all specs you need. When you go looking for this carb, look by model and make of automobile...most people look at you funny when you ask for a MC2100. They can't handle that much precision. Just tell them a make and model of auto then they'll say "Oh, yeah it's a MC2100" like they have superior knowledge. You just smile and pay the idiot.

GPERX4 04-08-2003 08:10 AM

I had a Mc 2100 1.01, but it wasn't big enough for my 258 so I found an old Ford pick up that had the 2150 1.08. I had to make a plate between the carb and the addaptor because it was curved and the carb was straight across the back.

Tmartin 04-08-2003 08:31 AM

The adapter you need is called larger two barrel to small two barrel adapter. Summit carries them if your local speed shop doesn't. Here's more info than you probably need:

Motorcraft / (sometimes called Autolite ) 2100 Carb Install on 258 Jeep

Parts List: MC2100 Carburetor, adapter, air cleaner assembly, throttle arm replacement (fabricated).

This 2bbl carburetor will replace the troublesome Carter BBD and produce a superior idle. It also appears to boost horsepower. It has a good reputation for being reliable and good off road. I am very happy with the conversion and thank all of those jeep enthusiasts who helped me with information on this swap.

This conversion will not meet with any legal requirements that prohibit the removal of original equipment or the tampering with emissions control equipment. Check with your local authorities if your vehicle will be subject to inspections in this regard.

The cost of this conversion will be approximately $150 or less using a junkyard carb you rebuilt yourself, rebuild kit, new air cleaner, adapter plate, and manual choke kit. You may opt for buying a rebuilt carburetor, and I would suggest that you order one made for an AMC 304.

1. Motorcraft 2100 Carburetor – Sources: AMC 304 or Ford 302. Unfortunately Motorcraft does not stamp 2100 anywhere I can see on these carbs. The correct size will have “1.08” in a small circle cast on the drivers side of the carb body, somewhat obscured by the accelerator pump linkage. As difficult as this is to measure in the junkyard, the 1.08 is the size of the venturis (the barrels). I have been advised that #108 is 450 cfm, #114 520 cfm, and #121 575. Use the 1.08. This carburetor body is cast from two pieces, a top cover and a combination baseplate / venturi / float bowl. Apparently you can set / observe the float height by idling the motor with the top cover removed. The top cover has the word “Motorcraft” cast into it on the passenger side above the float bowl.

Power Valve:

Be sure to replace the power valve on this carb. It’s function is to enrich the mixture as manifold vacuum drops (signaling load increase). It is closed at idle, and opens to add more fuel as the manifold vacuum drops. If it is not operating correctly, your mixture may be too rich. It is located on the bottom side (front) and is contained under a cap with 4 screws. There is also an accelerator pump on the front, also under a cover with 4 screws, but it is identifiable by the accell pump linkage. I have obtained good results using an oem 2 stage power valve. This valve is longer than the single stage and is original equipment. It is 39mm long from top to bottom and mine was labeled #16. I have been advised that this means that it will not enrich the mixture until manifold vacuum drops to 16 inches HG. I had to go to a carburetor rebuilder to get this part, it was $5.00. Take in your old one as a sample. A single stage may work fine as well.

2. Carburetor Adapter – It is the 2 barrel Rochestor to 2 barrel Holley adapter. Also known as the large 2 bbl to small 2 bbl manifold adapter. Summit sells TD Performance Products adapter no. TRD-2086 for $12.75. It comes with 2 gaskets. I replaced the slotted bolts that came in the kit with allen head bolts to make tightening the adapter to the manifold easier. I also used a hardening gasket maker instead of the gasket between the adapter and the manifold (Permatex Form a Gasket 1A). I also used a Ford gasket between the carburetor and the adapter. It is made of black plastic and looks like two gaskets sandwiched together with plastic bushings inside the stud holes. Is this gasket necessary? There is nothing special about it other than that it will seal very well and also provide a lot of heat insulation from the manifold. The hole in the adapter is slightly larger than the jeep manifold. I have thoughts to switch to an aluminum intake manifold from an 84 and blend the manifold to the adapter with a die grinder.

3. Air Cleaner Assembly – This carburetor has a much large air cleaner base than the Carter BBD. It is the standard 5 1/8 “ air cleaner base used on most 4 barrel carburetors like Holley’s. Unfortunately the close proximity of the power brake booster and master cylinder limit you to a 9 to 10” (9” preferred) open element air cleaner. If you swap booster to a dual diaphragm GM booster (a great upgrade) you will not be able to use a filter above the carb at all. A K & N 9” filter (2” height) with top and baseplate is $49.39 from Summit (pn. KNN-601110). I ended up fabricating an adapter to a K & N conical filter out of fibreglass.

4. Throttle arm – The OEM Carter uses a similar linkage, but pulls downward instead of the rear pull on the Motorcraft. You need to simply remove the throttle linkage ball stud from the Motorcraft, bolt on a small metal plate (1” by 3” and 1/8 thick) to the Motorcraft’s throttle arm with 1/8” bolts so it is rearward facing, and drill a new hole in that plate for the OEM throttle linkage. I would suggest bending a slight offset into the plate to move the ball stud slightly away from the carb to prevent binding of the linkage rod. In addition, bolt the plate on first then using the linkage rod, mark the plate for the new ball stud hole, remove the plate and drill the hole for the ball stud. Some people have removed the throttle arm from the old Carter BBD and bolted it on, but that seems like a waste of the old carb just to make a simple throttle arm with 3 holes in it. If you are not happy with this carburetor, you may need that old BBD back ( I doubt that will happen if you start with a healthy Motorcraft.)

5. Throttle return spring – I found that mounting the original downward pulling throttle return spring caused binding as it wrapped around the shaft. I instead fabricated a small bracket to bolt to a front bolt of the carb base to relocate the spring to the front.

6. Vacuum hoses – The motorcraft has two ported outlets. One on the front, just outside (to drivers side) of the drivers side venturi idle control screw. I used this ported outlet for my distributor. There is also a ported outlet on the passenger side of the carb base. I am not sure if there is any difference between these two. Mark all hoses you remove from the Carter BBD and connect them back up to the corresponding ports on the MC 2100. The only connection missing from the MC 2100 I used, compared to the Carter BBD is the vapour line running from above the float bowl to the charcoal canister for the collection of evaporated gas fumes. I would suggest plugging this line that ran back to the canister, as the MC 2100 vents the float bowl into the air cleaner housing.

7. PCV – There is a large PCV inlet port on the rear of the carb at the base. If you are looking in the junkyard for a MC2100 be sure that the version you take home is not an older one missing this port.

8. Idle Adjustment – Like most other carburetors there are two screws on the front base to adjust the mixture. Turning them in leans out the idle mixture. Never seat these screws with a lot of pressure at they are needles which will distort and damage the soft metal of the carburetor. I would start with around 2 turns out on each screw and adjust equally from there using a vacuum gauge attached to manifold vacuum to adjust for peak lean vacuum. In other words, turn them out till you get maximum vacuum, then turn them in till it starts to drop off, and back them out slightly from that point to regain peak vacuum. This carburetor is very forgiving for idle adjustments, so don’t sweat it.

9. Choke – There was an electric choke assisted by exhaust gas on both of the MC2100 I looked at. I tried the Motorcraft electric choke and it did not seem to work well so I used the Carter BBD’s electric choke by removing and reversing the bi-metal coil inside. This worked well till temperatures hit –30 degrees and I switched to a manual choke. I found the electric came off too fast in these cold temperatures and annoyingly came back on after short stops. The manual choke works well. The choke mechanism on my carb has a passage to the base of the carb where is picks up manifold vacuum. This draws heated air or exhaust from the larger fitting on the choke casting (which should also be capped off by you) and warms up the choke’s bi-metal coil. If you install a manual choke, you should plug the inner passage with epoxy or rtv sealant to reduce your idle speed and keep dirty air from entering the manifold.

10. Fuel line inlet – The original fuel line will work fine. You may want to replace the short metal section that screws into the float bowl with a brass fitting.

11. Ford Base plate – There is a cast aluminum base plate with a vacuum operated EGR assembly on it. These are common in the junkyards. As the oem gasket covers all of the bottom of the carburetor except the venturi openings I did not use the Ford base plate. I picked one up from the junkyard just in case. Using it will require lengthening the throttle linkage rod to compensate for its thickness.

12. Miscellaneous – The rebuilt carburetor I used has a small spring on the float assembly shaft which I am told is used to dampen the float movement for rough conditions. The other MC2100 I have for parts does not have this spring on the pivot shaft. Jets are probably available from Ford. They are the same size as used on the 4 barrel motorcrafts. After a winter’s driving I have examined the spark plugs and am happy with the jetting which is #47’s. Both MC2100’s from 304 AMC’s I have seen came equipped with #47 jets. I have found that for my application the accelerator pump linkage works best set to the third hole down from the top (of four holes) on the arm at the throttle shaft. It’s easy to tinker with to verify of this works best for you.

Tim Martin

timber-wolf 04-08-2003 12:48 PM


Originally posted by apeters89
ordered one from Autozone (for a 1978 AMC AMX w/ 304 V8) of all places... $160. I haven't had a lot of free time to work on my Jeep (putting tile in the house, myself) so I didn't want to bother with the rebuild. As soon as it comes in I'll figure out what adapter I need, and how to fix the throttle linkage.

Thanks for the info.

The only thing I see from AutoZone is the Champion Ford Model 2150. Is this the same as the MC 2100 or 2150? I've searched through several yards around here and haven't been able to find one... Is there a source for new or rebuilt ones online?


drewmandrews 04-08-2003 01:01 PM

BostonWrangler and TMartin posts above gives you all info you need...read with care, you can go hunting with engine specs or carb specs, either way read what they've said in their posts to you, you'll be fully armed. I wish I had that info when I started looking. When you find your carb, get two, I'll take another for a spare.

BostonWrangler 04-08-2003 02:49 PM

I think I have a very old 2100 series carb from a 60s something Mustang. Not really sure.

It definitely needs to be cleaned up a lot, but rebuild is so simple on these carbs. The throttle valves are rusty, but that's nothing a wire brush and brake cleaner can't fix. I'd recommend soaking the entire carb if possible.

It doesn't have a carb bowl vent, so if visual emissions are a concern, this probably won't work.

$35 shipped.

Brandon 06-08-2003 09:46 PM

281 Attachment(s)
Mine is from a 66 mustang, 1.08. I think I need to rebuild it though as the engine "bucks" meaning it doesn't like to go slow, slowly accelerate and it just jumps, not smooth at all. Can't think of what else it could be :(

Is one rebuild kit better than another? I have never had luck rebuilding carbs - they always seem to run worse. Should I just take it to a pro or try again?

Thanks! BTW I did not use a bottom plate, just the adapter and that is it.

BostonWrangler 06-08-2003 09:52 PM

Yeah, rebuilding the 2100 is super easy. Kind of hard to mess it up as long as you keep everything in order. Clean the mixture needles really well. Soak the small parts in brake cleaner. I use a coffee can or a small tinfoil cupcake tin type thing.

Make sure you use gaskets between all mating surfaces.

jeepguy553 06-08-2003 10:02 PM

I ran a 2150 on my 360 for two years...then I started upgrading to stuff like taller cams and better ignition. The 2100/2150 carbs are great. When you are rebuilding it, make sure you replace the annoying little check ball in the primary booster circuit. It can actually rust itself in place and give you freakin' fits when you try and start the engine. I had one do this to me on a Waggy I had and it drove me nuts for a week until I rebuilt the carb and found out what it was.
I've even heard of buys putting 'em on backwards and calling it "poor man's throttle body injection." I can't for the life of me see how that would work...but okay...

BostonWrangler 06-08-2003 10:52 PM


Originally posted by jeepguy553
I've even heard of buys putting 'em on backwards and calling it "poor man's throttle body injection." I can't for the life of me see how that would work...but okay...
Yeah, that sounds really poor to me.

Maine Jeepah 06-09-2003 06:03 AM

I bought mine at Auto Zone a few years back.
It was for a Ford Van with a 302 engine. I forget the specific year but it was late 70's or early 80's. Came with an exhaust gas actuated choke, so I bought a manual choke kit.
Also bought the 2 barrel to 2 barrel adapter plate from them.
Popped it on, rigged the throttle arm to work with the CJ cable,hooked up fuel, got a cheapo open elemnt filter assembly put a K and N in it and it has worked GREAT ever since.


Originally posted by timber-wolf

The only thing I see from AutoZone is the Champion Ford Model 2150. Is this the same as the MC 2100 or 2150? I've searched through several yards around here and haven't been able to find one... Is there a source for new or rebuilt ones online?


Rockcrusher 06-09-2003 07:28 AM


Originally posted by big bad Jeepster
They are a great carb! I run the 1.08 on my 225 V6. $30 from a wrecker and $20 for a rebuild kit. Much cheaper then buying a new/rebuilt one.
BBJ, did you have any problems with the throttle linkage? My old Rochester 2GC is getting pretty tired and since a 225 doesn't like EFI, the 2100 seems like the logical choice.

For everyone else, here's a breakdown of the 2100 CFM ratings

Bore CFM
0.98 190
1.01 240
1.02 245
1.08 287
1.14 300
1.21 351
1.23 356
1.33 424

mellocj 06-09-2003 08:22 AM

The adapter is part # TRD-2086 from Summit Racing.. about $13 + shipping.

la7 10-29-2009 03:56 AM

I am having a problem with the Motorcraft 2100 on my 258. It idles fine starts out fine but when I get into it it goes flat and as I let off a little it will pick back up. It is freshly rebuilt. Since the part are cheap it would be nothing to start replacing the parts but without knowing what is going on the lesson is lost. Any ideals?

99Jeeper 05-11-2010 09:34 PM

does anyone know if you can use 2100 to replace a carter 1barrel on an 85 xj 2.5l 4banger? pm please

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