Spark lever question

[Willynch]

To start, I retard the spark with the lever all the way up. Once the car starts, I advance the spark with the lever all the way down. Even when warmed up, if I try and move the spark lever up from the "all the way down position" the engines slows and stalls. In otherwords, it seems I can only run with spark advanced all the way.

I am rebuilding the carb because of leaks. Once that is completed, how do I improve the performance of the spark adjustments?

Thanks