Motorcraft 2100 carburetor

OK, so i got a 73 mustang with a 351C 2V topped with a Motorcraft/Autolite 2100 carb. My problem is that start up is ok, warming up is a killler problem and when its warmed up and the choke all the way open she runs like a dream. My question is does anyone know anything about these little beasts that call themselves carburetors and how to set it up to run smoothly through all stages of operation. Oh........and theres also a revving problem too with the thing........it will rev up, but when its coming down it starts to sputter and choke and sometimes even dies if i rev high enouhg........thanks to all that have any tips or comments or anything.


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There is a choke unloader (vacuum motor) on the right side of the carb. On cold startup, the choke flap will (should) be completely closed for easy startup. Once manifold vacuum is available, it will operate the pull-off ever so slightly (adjustible) to open the choke valve to get some air. If the pull-off doesn't work or is incorrectly adjusted, the fuel mixture will remain too rich until the choke stove finally pulls the flap open somewhat.

Take the air cleaner lid off (block all open vacuum lines) and start the engine. The choke flap should immediately open a predetermined distance (say 3/8"). If no movement after startup, this is most likely your problem.

Throw that 2100 as far as you can. All I can say about those damn holleys!

Ummmm...it's an Autolite carb although they do look a little like Holleys. They are great carbs, I have an old 350cfm version in the garage waiting for a special Ford engine to put it on, not easy to find the big ones anymore. Best part...most Autolite jets fit so finding a complete set of jets involves raiding old junkyard carbs to collect jets!

I am still looking for a nice 4100 or 4300 worth rebuilding, rare as hens teeth up here.

__________________
Outlawed tunes from outlawed pipes

Here 'ya go Chuck...For your personal reference;

The following I.D. Nos. (found on the side of the float bowl behind the accelerator pump rod) will give you the individual CFM ratings.

Stamped No + CFM

.98=190
1.01=240
1.02=245
1.08=287
1.14=300
1.21=351
1.23=356
1.33=424

The 4100 booster asms. interchange with the 2100 and a host of HOLLEY modifications can also be done on these two series.

That is an excellent carb. Trouble free when set up correctly. Get a kit and overhaul it and set it up PER ADJUSTMENT SHEET! Then adjust slightly from there if their is still a problem. The choke sounds like it isnt set properly, maybe the spring is wound wrong or has the wrong choke cover on it.

It's the same thing as a holley/motorcraft 2150, POS carbs in MY opinion. Extremely hard to adjust and get set right, always going out of tune if the weather changes by 20 degs or so and is a real fire hazard. BUT that is MY opinion and I'm sure you all are much better at tuning them than I.

Give me a CCC Q-jet anyday, just one screw to turn hehehe...

take it with a grain of salt guys.

The duke!

__________________
Outlawed tunes from outlawed pipes

Now if it was a 2700 or 7200 model Variable Venturi carb I would agree with a violent destruction of that carb in a manner that only Rambo could be proud of. Although ...even those can be set up in a reasonable manner. After all.........................a carb is only as good as the techs knowledge that's building it.

LOL (stares at the carburator with one eye slanted) "I'm your worse nightmare" BLAM BLAM BLAM BLAM!

hehehe... oh god I need a life!

Where did you get these CFM's? Can you verify their accuracy?

That vacuum break valve is one thing... but generally if you sputter when at high rpms it is your ignition that is to blame, or so i have heard. If the problem stops with higher RPMs it's a gas problem, if it continues at high RPMs it's an ignition problem.
It sounds like you might have a problem with your timing advance.

Your high rpm problem could be ignition overadvancing. Disconnect the vac advance and run the engine at 3000 rpm and check the advance compared to idle. Then at idle, hook up manifold vac or vac pump at 30" of vac, then recheck the advance, add the manifold advance and the vac advance to get total advance. It shouldn't go over about 30 degrees.
Or... just disconnect the vac advance and drive it around to recheck and see of it still has the the high rpm problem. This way you can eliminate the distributor advance as the cause of the problem.

All Ford 2V and 4V carburetor (mfg. since 1960) have 2 markings to easily determine what they are. On the drivers side of the carburetor - right behind the accelerator pump rod - you will find what appears to be a “clockface”. Inside the “clockface” in raised characters 4100’s will read 1.08 or 1.12*. Approximately one inch directly below the “clockface”, on the mounting flange (or toe) of the carburetor, there will be stamped on engineering number. The numerals in the “clockface” refer to the primary venturi diameter in inches. The “1.08” is a 480 CFM carburetor - while the “1.12” is a hefty 600 CFM. (In 1958 only Ford made a 1.19” venturi (670 CFM) you’ll probably never see one of these)


thought this would help your cfm question .

.98=190
1.01=240
1.02=245
1.08=287 (this one i own .)
1.14=300
1.21=351
1.23=356
1.33=424


just talked to autolite direct ....these are for the 2100



the above post is for the 4100.