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Motorcraft 2150 rebuild - alenoid gasket issues


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#1 BostonWrangler

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Posted 11 March 2003 - 10:26 PM

This is the third 2100 series carb that I have rebuild, but the first one with altitude compensation aneroid as far as I can remember. An important difference was that I had the help of a great young man by the name of Darek. He did a bunch of the work.

The gaskets that I removed from aneroid assembly were a lot thicker than the gaskets that were supplied with the Sorenson rebuild kit.

Is there a way to make a tight seal with these thinner gaskets or do I need to buy some bulk automotive gasket material and cut some matching gaskets to thicken it up?

What is the deal with this aneroid thing anyway? Is there a way to bypass it? The valve in there was sooty. I wiped it off and reinstalled it, but the spring in there doesn't push the valve back. Is it supposed to reseat the valve?

If anyone can explain a way around the aneroid or a way to make sure it is installed properly on my carb, I sure would appreciate it!

Thanks :blink:

#2 BobBarry

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Posted 11 March 2003 - 10:46 PM

I don't think gasket-thickness is all that crucial. That piston should move freely, though. I wiped mine down in a rag soaked with brake-cleaner. It also sometimes develops a "notch" from wear. I've just replaced the old one with a better one from another used carb.

You're welcome to rummage through my spare 2150 pile and use whatever parts you like; I'm about to upgrade to the world of Edelbrock, so I only need to keep one around as an emergency emissions-test visual-inspection backup.

#3 BostonWrangler

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Posted 11 March 2003 - 11:14 PM

Word up Doc

Thanks! Yeah the valve was pretty sooty as I mentioned. I wiped it with a towel, but I'll take it back out and wipe it down with some solvent. Is it supposed to look like it has a rubber coating on it or is it all that brass color?

Is there any way to clean the aneroid or is everything inside untouchable?

Why do you say that the gasket thickness isn't crucial? To me it looks like air could pass right by the gaskets and be sucked into the barrels of the carb aft of the venturis all the time if the aneroid gaskets don't seal properly, thus causing a lean condition all the time.

#4 BobBarry

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Posted 11 March 2003 - 11:28 PM

IIRC, how deep that aneroid assembly sits in the carb body is not a critical dimension, so the thickness of the gasket is not a high-tolerance matter. Obviously, the gasket would have to seal properly, or else there would be a massive leak.


OK, just to refresh my memory, I went into the basement workshop and looked at the one I had on my bench. The spring is retained to that center section in a little cage; you can pop off that cage and pull the piston out to clean it better. What you can't remove or disassemble is that rear aneroid assembly itself; it's sealed in the manufacturing process, and I wouldn't even try adjusting that little screw on the end.

The mystery of what is in there revealed itself on the parts-truck I had that was damaged by fire. There is a brass bellows in that rear housing. As best I can guess, it is sealed at a certain atmospheric pressure, so that any change in external pressure causes an exagerrated expansion or contraction of those bellows, which moves that piston to admit extra air and avoid running rich at higher altitudes.

For all practical purposes, at our sea-level use of these trucks wouldn't engage that altitude compensator, so its proper operation on our trucks is far from critical.

#5 BostonWrangler

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Posted 11 March 2003 - 11:41 PM

But if the valve is stuck in the open position, it would lean out the mixture all the time.

I adjusted the screw on the end tonight to the "all the way out" position. The screw only turned about 1/2 to 3/4 of a turn and I can still see where the threads are cleaner from having been screwed in for the life of the carb. I can easily screw it back in to the original position.

The reason the thickness of the gaskets is a concern to me is that the aneroid is not sealing properly to the valve assembly and the valve assemble is not sealing properly to the carb body. Should I make new homemade gaskets to double-up the gaskets from the rebuild kit? I think this will properly seal the whole shebang.

I may end up making a sheet metal block-off plate and install that in place of the valve assembly. The next time I plan to drive at high altitude, I can install the aneroid assembly :blink:

We'll see how it goes.

#6 Darius

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Posted 12 March 2003 - 06:45 AM

This is the third 2100 series carb that I have rebuild, but the first one with altitude compensation aneroid as far as I can remember.

The gaskets that I removed from aneroid assembly were a lot thicker than the gaskets that were supplied with the Sorenson rebuild kit.

Is there a way to make a tight seal with these thinner gaskets or do I need to buy some bulk automotive gasket material and cut some matching gaskets to thicken it up?

What is the deal with this aneroid thing anyway? Is there a way to bypass it? The valve in there was sooty. I wiped it off and reinstalled it, but the spring in there doesn't push the valve back. Is it supposed to reseat the valve?

If anyone can explain a way around the aneroid or a way to make sure it is installed properly on my carb, I sure would appreciate it!

Thanks  :wub:

:blink:

#7 Darius

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Posted 12 March 2003 - 11:25 AM

:blink:

#8 BostonWrangler

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Posted 12 March 2003 - 05:08 PM

Darek- I stripped one of the mounting points on the aneroid thinger.

But, I made 2 gaskets from some flat gasket material and that seemed to work pretty well. I got everything installed. I made sure that the idle screws were backed out 1.5 turns and tried cranking the thing over.

After a few cranks to get the bowl full of fuel and a few squirts of starting fluid, she fired up. A lot of white smoke from the tailpipe but the engine revved up nicely.

And once it was warmed up, I took it for a spin and it idles so nicely now! I don't have an exact number for the idle speed cuz I don't have a tach, but it is nice and low and sounds like, "rum rum rum rum rum rum rum rum." So steady and soft. I love it!

Thanks for your help Darek!

Now I need to patch the leak in the metal fuel return line along the frame above the front axle!!!

#9 Darius

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Posted 12 March 2003 - 07:04 PM

ASWOME! Glad to hear you got it working. Was damn near easy to rebuild it, wonder why I ever gave mine to the mechanic 2 years ago. :lol:

#10 Yard Bird

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Posted 13 March 2003 - 02:09 PM

When I bought my Jeep from the PO, he gave me a buch of JP mags. I was looking through one while I was home sick this week and saw a whole article on this carb being rebuilt with lots of pics. I want to say it was in the Sept '01 issue, but not too sure. The rebuild is pretty simple with these carbs.

HTH

Rob

#11 BostonWrangler

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Posted 13 March 2003 - 08:10 PM

:P

#12 Flat Belly

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Posted 14 March 2003 - 01:24 PM

Save the gasket and compare it against the gasket supplied in your rebuild kit. If the original gasket is thicker than the new supplied gasket and it's in good shape, reuse the old gasket. The original gaskets are ~.050" thick while all the gaskets I've encountered from rebuild kits are ~.030" thick. It's critical this housing seals. The carb. won't perform well otherwise. If you suspect a slightly warped surface which identifiable by being able to jiggle the gasket, especially at the bottom, once the 3 screws are tight on reassy.; use RTV Silicone on reassy. Lightly coat the lip on the valve housing side of the gasket. The lip is contiguous except around the bosses for the three screws.



That was taken from this rebuild guide http://www.ifsja.org...fuel/2150.shtml
Looks like you did the right thing to me.