In Feb 2018, in a thread: "Cold Start Problems", Martin Jansen, "Frameman", wrote:
".... On BJ8 carbs, the manual says to set float levels at 7/16ths, reset them at 5/16ths which will raise the fuel level in the float bowls. Next check to see if jet needles are located properly and make sure they are both set at same height, with the slides out look down into the jet orfis. Look at the fuel level , it should be 1/8 to 3/16th of an inch off the bridge of the carb body where the jet fits. The jet should be 1/16th of an inch from the carb body. I just finished doing a car that would not start in 60 degree weather after I did this fix the owner said he started the car no problem in -30 c. I have done this to many cars with complete success. Then tune carbs accordingly."
I can confirm this. When I adjusted my floats to give the 3/16" fuel level in the jets, as advocated by Tony "Ozhealey", the resulting float level is 5/16", not 7/16".
In addition, with Tom Bryant's line bored delrin bushings, the slow run screw becomes functional, allowing a range of idle adjustment without the previous cracking of the butterflies.
NFI.
https://thosbryant.wordpress.com/category/su-carburetors/
I have to conclude there was previously a little air leakage with my new stock bushings installed last year.
Where we differ is my jets are set to .083" down vs his at .0625" (1/16")