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post #1 of (permalink) Old 09-16-2006, 05:26 AM Thread Starter
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Stuck throttle plates on MC2100

I went to the Jyard and bought an MC2100 from an F-250. The throttle plates were stuck shut so the guy gave the carb to me for 15.00. Excellent price. Well, the carb is now torn apart as I am in the middle of the rebuild. I finally was able to pound out the throttle plates with a little piece of wood and a hammer. The shaft that the plates bolt to does not budge, nothing at all. Are there any special tricks anyone knows of to un stick the throttle shaft? A guy told me to soak it in brake fluid so I am trying that right now, as I wait. Thanks
Tim
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post #2 of (permalink) Old 09-16-2006, 07:33 AM
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Re: Stuck throttle plates on MC2100

Brake fluid doesn't make any sense to me. There are lots of products designed for the purpose. My favorite is Kroil penetrating oil, and PB Blaster gets many recommendations from others here.

Heat, vibration and patience are your friends. Put the plate in a vice and heat the area around the throttle shaft with a propane torch while tapping gently on the ends of the shaft with a small hammer. If it hasn't moved by the time the base plate gets good and hot (don't let it get hot enough to glow) let it cool. After it cools a while, but is still a little too hot to touch, apply your penetrating oil and keep tapping until the plate is cool. Repeat until it moves.

Probably the carb was sitting exposed to rain, which caused rust between the shaft and its bore. Once you get the shaft moving it might be sloppy loose. If it is, air can get sucked around the shaft messing with the mixture. The engine might never idle well, although it will probably run fine at anything above idle.
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post #3 of (permalink) Old 09-16-2006, 08:08 AM
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Re: Stuck throttle plates on MC2100

Well, I didnít want to be the first bearer of bad news so I waited for somebody else to break it to you. All is not lost though.

Squirt it with PB Blaster several times where the shafts go through the base. Squirt it again tomorrow and the next day. Then try to move the shaft. If it doesnít move by hand squirt it again and let it set another day. Eventually the shaft will move DO NOT USE HEAT.

Now that you got the shaft to move, you have a core. Reassemble it and take it to AutoWhatever and trade it in on a rebuilt. From where you are at, you will probably never get it right. You might have a vacuum leak around the shafts, you may never get the plates back in close to right, and/or you may have slight binding of the shaft and/or throttle plates.

To remove the plates, you must have removed the screws that were bradded over on the ends to keep them tight. If, as most people do, you just unscrewed them, you distorted that little bit of threads in the shafts.

Itís just too much trouble to get it back right from where you are. To do it right, youíd need a new shaft, plates, and screws. Then you would then have to drill out the shaft holes in the base plate and install bushings. Then ALL of that is assuming that there is no pitting of the bores in the base plate.
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post #4 of (permalink) Old 09-16-2006, 08:51 AM
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Re: Stuck throttle plates on MC2100

I'd take it back and tell him to get you one that wasn't rusted up. I've seen perfect (Junkyard) condition MC2100's for $20. Ones that you could bolt right on the intake with no rebuild needed. Granted a rebuild is a good idea so it's not an unkown qty. In my opinion $15 for a posibly rusted up MC2100 isn't a good deal to be honest. Sorry man.
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post #5 of (permalink) Old 09-16-2006, 09:01 AM
 
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Re: Stuck throttle plates on MC2100

I agree $15 is no bargain. I found mine on eBay and got it delivered to my door for $30 ready to go in like new condition. If I were trying to fix one like yours I'd start by soaking it in carb cleaner for a day or two but they're so common, got get another one.
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post #6 of (permalink) Old 09-16-2006, 10:33 AM
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Re: Stuck throttle plates on MC2100

[ QUOTE ]
DO NOT USE HEAT

[/ QUOTE ]

Why not? I've never had a throttle shaft that needed it, but can't imagine the amount oof heat I suggested (not hot enough to glow) causing a problem. It's just cast iron and steel, at least every one I've ever seen.
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post #7 of (permalink) Old 09-16-2006, 01:22 PM Thread Starter
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Re: Stuck throttle plates on MC2100

ok thanks. the guy had another MC2100 but it had 1.21 venturi's. Can I use the venturis outta the one I got now in that one?
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post #8 of (permalink) Old 09-16-2006, 01:41 PM Thread Starter
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Re: Stuck throttle plates on MC2100

Never mind, I just thought about that. [img]/ubbthreads/images/graemlins/crazy.gif[/img]
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post #9 of (permalink) Old 09-16-2006, 01:54 PM
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Re: Stuck throttle plates on MC2100

You can rebuild what you have but I doubt that it would be worth the effort ...... I vote for the using it as a core for a rebuilt one.
If you want to rebuild what you have, patience, patience, patience .... it's not going to be an afternoon job ..... tap with hammer not HIT with hammer, soak & soak & soak with blaster or Wd-40 or anything else. I'm with Jim Lou, heat is ok (low heat). Works great on rusted up items (brake lines, bleaders, nuts, bolts)

Good luck
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post #10 of (permalink) Old 09-16-2006, 02:33 PM
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Re: Stuck throttle plates on MC2100

IMHO, this is a $15 learning experience. It's time to gain experience on this carb. Once you get it done, you'll be able to field strip that carb and put it back together blindfolded. That's pretty cheap experience for $15. It's far more valuable than trash, or for a core. Also, inexpensive parts can be found in a FOMOCO MC2150, the carbs are almost identical.
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