Cold start problem
So I'm having a little trouble with my cold start. It's a 4.2L with a weber 32/36 (electric choke) carb.
Let me start by saying this, after she warms up and the choke is out of the picture, she runs very smooth. As far as I can tell when warm she's running at a satisfactory air/fuel ratio because the acceleration is smooth and there are no pops or hesitations or backfires and right after a cruise I can check the plugs and they look great (mostly white but with a touch of tan).
The problem is when I cold start, I will:
1. Turn the key to on
2. Pump the gas one time to prime the carb and close the choke.
3. Start her up
She starts immediately, sounds great, and the cold idle works good holding the idle about 500-700rpm higher than the regular warm curb idle (not exactly sure on the rpm because I am skeptical my tach is working properly). BUT, after about 5 seconds of great cold start action she starts to buck and does not run smooth at all. She will keep running but it seems that she it too rich because if I open the choke by hand during this period she smooths out and sounds great, also she is coughing black smoke out the exhaust during this time, but after she's warm the exhaust is white and barely noticeable.
Could this be a choke setting problem because of the fact that she runs perfect when warm? or might this be a problem of too much fuel delivery? Because the choke seems to be operating fine (closing fully at cold start and slowly opening over a few minutes of running)
I apologize for the lengthy explanation, but I thought it would be beneficial to get all the info out there right away. I would really appreciate some help or input on this. Thanks