Resolved! Motorcraft 2100 problem
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Junior User
Joined: Sep 2007
Posts: 62
Likes: 1
From: Patterson, CA
Resolved! Motorcraft 2100 problem
Great success! I rebuilt the carb and changed the coil and now it runs like a top! Smooth idle, strong acceleration, easy starting, etc...
One more question about the 2100 carb. Which way do I turn the mixture screws to lean out the mixture, in or out? I gently seated them and then turned them out 1 1/2 turns and it seems a little rich.
Thanks to all who assisted with advice, you guys are the best!
One more question about the 2100 carb. Which way do I turn the mixture screws to lean out the mixture, in or out? I gently seated them and then turned them out 1 1/2 turns and it seems a little rich.
Thanks to all who assisted with advice, you guys are the best!
Post Fiend
Joined: Sep 2007
Posts: 6,221
Likes: 6
From: Cow Town, CA
i dont know exsact but here is what i found by doing a quick search...
After the engine is warm, turn it off and find the "mixture screws" 1 per barrel underneath the fuel bowl. Turn the screws all the way in, but be gentle (you could damage them).
Then turn them out 2 full turns be sure that they are equal.
Start the engine and set the curb idle by adjusting the screw on the throttle arm.
Now adjust the 2 "mixture screws" together in or out to obtain the highest vacuum reading.
You may need to readjust the curb idle screw during this to obtain the correct rpm.
i am not sure if this helps at all but...i would say in would be lean and out is rich(dont quote me)
After the engine is warm, turn it off and find the "mixture screws" 1 per barrel underneath the fuel bowl. Turn the screws all the way in, but be gentle (you could damage them).
Then turn them out 2 full turns be sure that they are equal.
Start the engine and set the curb idle by adjusting the screw on the throttle arm.
Now adjust the 2 "mixture screws" together in or out to obtain the highest vacuum reading.
You may need to readjust the curb idle screw during this to obtain the correct rpm.
i am not sure if this helps at all but...i would say in would be lean and out is rich(dont quote me)
Fleet Mechanic
Joined: Dec 2006
Posts: 1,338
Likes: 6
From: UPSTATE NY
yup i bought a vacuum gauge for 10 bucks at harbor frieght. it sure gets you dialed in. and i almost won an exhaust analyzer on ebay for 40 bucks but some fellow beat me within the last minute
Last edited by Danger_Dave; Jan 23, 2008 at 09:27 PM.
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Junior User
Joined: Sep 2007
Posts: 62
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From: Patterson, CA
Did the vacuum gauge method as explained above this afternoon (in the rain.) The exhaust still smells like it is running really rich.
I rechecked the timing and all of the ignition parts (cap, rotor, plugs, wires, coil, ignition module) are new.
I didn't regap the plugs wider after I installed the Pertronix kit or the hotter coil. They are still set for the points/condenser ignition.
Could this be why my exhaust smells so rich? It idles great, accelerates strong, starts quickly, but really stinks...
It is pretty bad. Any other suggestions?
I rechecked the timing and all of the ignition parts (cap, rotor, plugs, wires, coil, ignition module) are new.
I didn't regap the plugs wider after I installed the Pertronix kit or the hotter coil. They are still set for the points/condenser ignition.
Could this be why my exhaust smells so rich? It idles great, accelerates strong, starts quickly, but really stinks...
It is pretty bad. Any other suggestions?
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Junior User
Joined: Sep 2007
Posts: 62
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From: Patterson, CA
I tried leaning the screws out 1/4 to 1/2 turn in and the vacuum fell off about an inch or so. It idled slightly rougher also. I don't think the jetting would be off. The engine is stock and so is the carb.
Maybe hotter plugs or wider gaps, or both?
Maybe hotter plugs or wider gaps, or both?
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Cargo Master
Joined: Sep 2004
Posts: 2,691
Likes: 6
The screws only help you with idle. They control the amount of air flowing into the carb while idling. As you screw them in they plug the holes and you will kill the idle. You back them out until you have a smooth idle.
If you want to lean the air/fuel mixture that is being burned in the engine because your spark plugs are all black, then you need smaller carb jets. Those are the two brass things that you saw in the bottom of the fuel bowl when you did the rebuild.
If you want to lean the air/fuel mixture that is being burned in the engine because your spark plugs are all black, then you need smaller carb jets. Those are the two brass things that you saw in the bottom of the fuel bowl when you did the rebuild.
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Fleet Mechanic
Joined: Aug 2007
Posts: 1,838
Likes: 262
From: Piney Woods of East Texas
True, but if he has a bad power valve could make it run rich to. But I would not consider leaning one out unless someone messed with them earlier. In the 70's we had a lot higher leaded octane fuel. I was forced to richen mine up when I got it to keep it from pinging. In any case he should not change it more than 3 sizes at a time. At these smaller size jets it does not take a large jump to make a big change. You want to limit the change below 5% max. But I would make sure the ignition system is good a strong before that. A weak coil can make a engine indicate it is running rich. My MSD has a burn duration of 20 deg for any rpm under 3k. So it seams to burn the plugs clean all the time.
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Junior User
Joined: Sep 2007
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From: Patterson, CA
I don't recall from the rebuild, but are the jet sizes stamped on the jets themselves?
I may try jetting it down a couple of sizes when the rain stops. Can I get them from NAPA?
I don't suspect anyone has changed the jet sizes, but, the carb may have been originally off of a 351 or 360. I got the carb with an old donor SBF engine. It's on my small 302. That may be the difference now.
I can't think of any other thing that would make it run so rich. Like I posted before, all of the ignition components are new, including a hotter coil.
I'll let y'all know after the weather clears up a bit out here.
Thanks again
I may try jetting it down a couple of sizes when the rain stops. Can I get them from NAPA?
I don't suspect anyone has changed the jet sizes, but, the carb may have been originally off of a 351 or 360. I got the carb with an old donor SBF engine. It's on my small 302. That may be the difference now.
I can't think of any other thing that would make it run so rich. Like I posted before, all of the ignition components are new, including a hotter coil.
I'll let y'all know after the weather clears up a bit out here.
Thanks again
Fleet Mechanic
Joined: Dec 2006
Posts: 1,338
Likes: 6
From: UPSTATE NY
yeah bro i'd definitely look into changing those jet sizes. i have an edelbrock with a little assortment of jets and various parts, and after tweaking it my mixture is so dialed in. not only does it romp but i get 14 mpg. my buddy used to talk trash, and he has a gmc dinali with 24s and gets the same gas mileage haha.
Elder User
Joined: Jul 2006
Posts: 930
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From: East Helena MT
Be careful removing your old jets! They do make a tool for them but I have always used a big bladed flat screwdriver with no problems yet. Those little buggers can get stuck in the main carb body especially if they have not been removed in a while and since they are made out of a soft metal you can round off the slot in the jet. When that happens the screwdriver just slides right up out of the slot and it makes it very difficult to remove it them.
I have never bought jets for a Motorcraft carb but the over all design of it resembles a Holley 2 barrel. If he can’t find jets for a Motorcraft I wonder if Holley jets would thread in? It’s just a thought.
Jeff
I have never bought jets for a Motorcraft carb but the over all design of it resembles a Holley 2 barrel. If he can’t find jets for a Motorcraft I wonder if Holley jets would thread in? It’s just a thought.
Jeff
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Junior User
Joined: Sep 2007
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From: Patterson, CA
Originally Posted by bigblockford_390
Be careful removing your old jets! They do make a tool for them but I have always used a big bladed flat screwdriver with no problems yet. Those little buggers can get stuck in the main carb body especially if they have not been removed in a while and since they are made out of a soft metal you can round off the slot in the jet. When that happens the screwdriver just slides right up out of the slot and it makes it very difficult to remove it them.
I have never bought jets for a Motorcraft carb but the over all design of it resembles a Holley 2 barrel. If he can’t find jets for a Motorcraft I wonder if Holley jets would thread in? It’s just a thought.
Jeff
I have never bought jets for a Motorcraft carb but the over all design of it resembles a Holley 2 barrel. If he can’t find jets for a Motorcraft I wonder if Holley jets would thread in? It’s just a thought.
Jeff
Fleet Mechanic
Joined: Aug 2007
Posts: 1,838
Likes: 262
From: Piney Woods of East Texas
When there stuck like that use a hammer impact driver use on motorcycles. These most always work, if you provide enough downward force to make sure the bit does not slip. The jets are made of brass. Holly jets will work on any I have worked on.
Sometimes if you can get a helper you can do the same thing with a large screwdriver. One work on holding the screwdriver down with just a little ccw torque while the other person taps the head of the screwdrivers.
You may be able to use dremiel tool and cut new slots or clean up the one you messed up.
These jets are straight cut so hollow grounds bits woek best, they don't walk up.
Sometimes if you can get a helper you can do the same thing with a large screwdriver. One work on holding the screwdriver down with just a little ccw torque while the other person taps the head of the screwdrivers.
You may be able to use dremiel tool and cut new slots or clean up the one you messed up.
These jets are straight cut so hollow grounds bits woek best, they don't walk up.