Barry Grant Demon carb

[gilby246]

Hope someone can help me out. Have been reading this board for a while but this is my first question I have posted

anyway

I have a Demon 850 cfm w/vac secondaries and an electric choke on a caddy 500ci
I have the the thing all tuned correctly and runs great. The problem is getting the engine started when cold. Ill turn the key and hit the gas to set the electric choke. when it first starts up it runs very very lumpy and spews rich black smoke out the pipes. I need to keep my foot lightly on the gas so it doesnt die on me.Once the butterfly starts to open just a bit it leans out and runs great but then ill still have to continue to hold the gas because the "fast idle" is not working. I messed with the fast idle screw a bit but not fully understanding how it works and exactly what it affects I dont want to mess with it to much. I have also tured the black choke horn both clockwise and counter clockwise but still have a lumpy smoky start up and need to sit there till up to temp..
When it comes to Demon carbs im not very knowlegeable. I have bought the book and read it a few times but have not found the answers im looking for (or im overlooking them). I dont find the book to be very specific in what I am looking for.The only time i have to call BG tech is the weekends and there is never an answer.

I would appreciate any tips or suggestionss you guys may have