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'New' Carb. soot on driveway whilst on choke - Help

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Old 06-22-2013, 03:54 PM   #1
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Default 'New' Carb. soot on driveway whilst on choke - Help

I've just replaced the QJet on my 1974 350 Auto. - It wouldn't idle when hot - turns out the air horn was warped.

So I've got a replacement from a 1975 Auto. This carb. is a big improvement, starts from cold first time, idles smoothly when hot (or cold) and the idle mixtures screws are responsive (which the old one were not).

The ONLY problem with it is that is leaves soot markson the drive from the exhaust tips when I back it out of the garage from cold. I guess it is too rich when on choke.

I have an electric choke fitted (which works fine in terms of getting the car running when cold) - I've tried truning it clockwise to 'lean' out the choke, but that doesn't seem to stop the black marks on the drive (that I'm sure the wife will not be impressed with when she works out what is doing it ).


Constructive comments please - (change the carb. is only partially useful!).
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Old 06-22-2013, 07:34 PM   #2
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If this is not a winter or daily driver I would remove the choke all together. Just take out the choke "plate" in the throat of the carb by removing the two screws holding it on would be the easiest way. Careful you don't drop the screws into the carb. To be safe stuff a rag in the throat while removing the screws so if you do drop one it is in the rag and not down the intake manifold.
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Old 06-22-2013, 07:46 PM   #3
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Without trying to teach his grandmother how to suck eggs, I assume you have adjusted idle mixture screws for best vacuum etc? How far out from seated are they?
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