Some more info would be helpful. Color of smoke....any blue or just black (Carbon)? Imagine it's from the back cylinders? Did you add both pipes/mufflers new or use the original pipe/muffler and add a new pipe to the front header? How much did you drive it.....get it up to normal operating temperature?

I've used the Holley/Weber...out of the box it was great....wouldn't think it would be a problem if the car idled correctly. My old Rochester had run so rich for so long that I had accumulated significant carbon buildup visible in the exhaust ports. It took awhile for it to clean up......you can do some decarbonizing but don't want to get into that at this stage.

You might pull the plugs and compare the color of the electrodes....they really shouldn't be too black unless the float was stuck on the new carb and then you should be getting black smoke out of both pipes. I have a lotta faith in the H/W, especially if it's good at idle.

Give us a little more info and I'm sure some of the other guys will jump in with some fresh ideas. Hope this helps.

Dave

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