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66 289 2100 Carb, runs rich after rebuild


Ok, so its not a Mustang, its a pre Mustang, 66 Falcon, but everything about it is the same as a 66 mustang.

I am pulling my hair out, rebuilt the carb, checked everything, and now no matter how I adjust the float, or the idle jets, it burns rich, black smoke bellowing out the exhaust, and runs like crap. I had another carb on it but found it didn't match the manifold, and there was an air leak. Funny enough i drove it that way for 4 months... (ya it sounded like it was sucking air, but i needed to get to work)

Any suggestions on what I might have screwed up? It was running fine before the rebuild, my points had closed, but I thought it was a gumbed up carb, and thought well its always good to rebuild the carb just as a preventative measure...  Any Ideas would be apprecitated.

Did you change the jets?  If not, that isn't an issue.  So, now it sounds like your float is set too high.  Throw that black plastic float away and get a brass float.  Now, to set the float......Make for certain that you have the right rebuild kit.  Money should not be an issue here.  You need to have the correct power valve, etc. 
 Set the float level (dry): Measuring from the top of the float itself, 1/8" from the end or tip of the float, to the machined gasket surface on the float bowl (gasket removed) with the float in the up or shut-off position; the distance should be .555" (or 9/16"). A thin plastic ruler is included in the rebuild kits to facilitate this measurement.

I find it easiest to hold the carb body upside down, over the top of my head, to measure the distance.

- Mark the thin plastic ruler with a pen.
- Then holding the ruler, invert the carb. over your head which moves the float to the shut-off position
- Position the ruler so it just touches the top of the float ~1/8" from the end.
- Note your marked line relative to the machined gasket surface and then set the carb down right side-up on your work surface.

If the distance is less than 9/16" (float level too high), the tang which the needle valve hangs from on the opposite side of the pivot from the float needs to be bent downward some. Vice versa for distances in excess of 9/16".

No, didn't change jets, and a mechanic friend looked at them and said they are tiny, maybe even too small, but no i didn't change them. I did try to clean them however, and wonder if somehow I had wrecked them? Don't think so but it is a possiblility.

I wonder about the fuel pump, and have a pressure gauge, so will do a pressure test and see if everything is in spec, but don't think that is the problem. Another thread you answered talked about gaskets, so I have made a couple of new ones top and bottom or the riser above the manifold and will try that.

I will concentrate on the float level and gaskets and see where that leads me, my mechanic friend will come back and have a look once the carb is on the car... thanks for the response, will let you know what I find.

You will probably want to check the float prior to putting it back on the engine.  It sounds like this is the culprit.  If you have not changed the fuel pump then I doubt that is the issue.

What did you clean the jets with?


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