A very difficult motor to adjust properly.
You must break in 10 gallons @ 32:1.
Ducting is a must, and the rear carb must be set approximately 1/8 turn richer at the high end for cooling not to advance timing. Set the low end at 1/16 leaner for better mid range. Since the rear cylinders run hotter the fuel air mix requires less at the low end. Get as much airflow over the rear cylinders as possible.
Mark