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It's ALIVE! Motorcraft 2100 on a slant
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Author:  coconuteater64 [ Wed Jul 22, 2009 9:58 pm ]
Post subject:  It's ALIVE! Motorcraft 2100 on a slant
I got my slanted truck out of the driveway for the first time, under its own power! :mrgreen: I had to drive it to work today because I had nothing else. It fired right up, and sounds mean!

Problem: when I accelerate from idle, either a little throttle opening or a lot, it stumbles and die if I don't mash the clutch back in and "feather" the throttle. When it gets to about 3000 rpm, it pulls like a rocket. But no matter what, it has a stumble on take off.

Timing was dead on 12* BTDC before the carb swap, and I didn't mess with the dizzy. Vacuum advance works (checked it with the cap off while applying vacuum). Accelerator pump is set on the center hole. It does idle a little high, and I can't seem to get it any lower than 1200rpm.

Any ideas?
Author:  wjajr [ Thu Jul 23, 2009 4:22 am ]
Post subject: 
My car was doing the same thing, but not as bad as yours though. Most likely she's suckin air... Look for a vacuum leak, and also asses your accelerator pump shot after you find the leak.

I pulled my hair out looking for a vacuum leak on my heap, as well as emptying several cans of carburetor cleaner around my Holley during the discovery phase. After pulling the carburetor & using a good straight edge, I discovered its base was concave allowing air in all four sides at the manifold. When the base was sprayed, the other three air suckin sides picked up the slack allowing no rpm change.

Other places to look are: proper connection of PCV valve; power brake booster vacuum problems; and that all unused vacuum taps on the carburetor are fully capped off.
Author:  SlantSixDan [ Thu Jul 23, 2009 6:40 am ]
Post subject: 
Congrats. Where do you have your vacuum advance hooked up? I was under the impression the #2100 doesn't have a ported vacuum tap.
Author:  coconuteater64 [ Thu Jul 23, 2009 3:13 pm ]
Post subject: 
Quote:
Congrats. Where do you have your vacuum advance hooked up? I was under the impression the #2100 doesn't have a ported vacuum tap.
There is a port on the side of the carb right under the choke housing. That's the only vacuum port on this carb. I just assumed it was ported, since that is where the Ford distributor hooks to.

That would make sense, as would the vacuum leak suggestion. Guess I will have to check both tomorrow when I get home from work.

Sure pulls strong from mid-throttle though! :D
Author:  kesteb [ Thu Jul 23, 2009 9:13 pm ]
Post subject: 
What adapter plate did you use?

I made my own as the store bought ones are prone to leaking, as they are for the Holley 2300, which has a different base plate. Ford used full vacuum on there distributors, there is no ported vacuum on the 2100.

The stock jetting is fine for a stock engine. With my Dutra's and 2 1/2" exhaust, I had to increase the jet size by 2 numbers, even with that there is still a slight surge around 1500 rpms, a slight tweak of idle screws would fix the problem. Jets and other parts can be had from Pony Carbs.

I love my 2100, I have been running it now for 2 years. Noticeably increase in performance and gas mileage as compared to a BBD.
Author:  coconuteater64 [ Thu Jul 23, 2009 10:58 pm ]
Post subject: 
Well, that might explain it! If Ford uses full-time vacuum for the distributor, and Mopar uses ported vacuum, that might be the culprit.

So, what vacuum source could I use for my distributor? There are no other ports on this carb.
Author:  kesteb [ Fri Jul 24, 2009 6:13 am ]
Post subject: 
Since you have no power and a high idle, I would suspect the adapter. If you do a search of the Jeep forums, you will find that a lot a people have had problems with vacuum leaks.

For example the Jeep guys say the Mr Gasket adapter is better then the Transdapt one. Both have problems, that's why I made my own from 1/2" plate aluminum

The 1.14 size is fairly rare, what vechicle did it come off of?.
Author:  coconuteater64 [ Sun Jul 26, 2009 4:16 pm ]
Post subject: 
My adapter is made from 1/2" billet aluminum. I checked and there are no vacuum leaks anywhere. The full-time vacuum from the carburetor was causing timing problems. I thought it was a timed port, but since I have learned that it is indeed manifold vacuum. I am going to get a Holley 2300 as soon as I can afford it.

The carb came off a `66 Falcon.
Author:  wjajr [ Sun Jul 26, 2009 5:16 pm ]
Post subject: 
Quote:
The carb came off a `66 Falcon.
Oh, Oh...

An other Falcon by Ford.
Author:  kesteb [ Tue Jul 28, 2009 9:52 pm ]
Post subject: 
What size engine did the Falcon have? Why get a Holley 2300? It is basically a performance carb. The 2100 is a better carb for general purpose usage.

You only really need vacuum advance when you are doing steady state crusing. For most stop and go driving, it never kicks in. What are your drving habbits?
Author:  coconuteater64 [ Tue Jul 28, 2009 10:46 pm ]
Post subject: 
I drive almost 50-50 interstate and city. I need all the gas mileage I can muster, but I can't just "putt putt" around. Gotta have some semblance of performance.

I didn't take my carburetor choice lightly. Jeep guys love the 2100; it's just the vacuum advance thing I didn't research until after I drove it twice. Oops! :oops:

I love the MC 2100 for its simplicity. Had a few of them over the years and they tune nicely. But if I can grab a Holley 2300, so much the better. Will go well with my dual Dutra manifolds, I hope.
Author:  cavisco [ Wed Jul 29, 2009 4:21 pm ]
Post subject: 
I found this on one of the jeep forums concerning ported vacume on the MC2100:

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.

Don't know if you have already tried this, but maybe this will help.

Scott M
Author:  coconuteater64 [ Wed Jul 29, 2009 4:26 pm ]
Post subject: 
Quote:
I found this on one of the jeep forums concerning ported vacume on the MC2100:

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.
Not present on my carb. There is only one vacuum port on it, period.
Quote:
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.

Don't know if you have already tried this, but maybe this will help.

Scott M
The only port I have is on the passenger side, but it is not on the base. It is on the side of the carb about halfway up. It is full-time (manifold) vacuum. It is now plugged, and I really don't like the way it runs with no vacuum advance. Hence, the 2300. My carb is from 1966, so it is devoid of emissions gobbledygook. I will either have to find a newer one with ported vacuum and rebuild that one, or save my coins for the 2300. I would really rather have a 2100 due to costs and simplicity, but the "tweakability" of the 2300 is mighty tempting!
Author:  kesteb [ Thu Jul 30, 2009 10:11 pm ]
Post subject: 
Tweak ability, there is at least 20 different versions of the 2100/2150. Ford used them on everything from 4 bangers to the 429. Jets are readily available in multiple sizes. There is a least 30 different power values, both 2 stage and 3 stage. About the only thing you can't easily tweak is the accelerator pump. You only get 3 holes on the lever...
Author:  coconuteater64 [ Fri Jul 31, 2009 11:57 am ]
Post subject: 
Guess I might have to find one that has a ported vacuum and start over. Sigh.
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