Tuning issue on a 440

Carfreak.
Yes the rods MUST be down at idle. In a nutshell, you want the strongest springs that will keep the rods down at idle.
I think you need to change the centri curve. You are getting half of the centri timing in by 1600. If you can reduce that with a heavier spring, I am sure it would help.

Comment about the carb. I hope yours has conventional idle mixture screws [ two ] at the carb base. Some AVS carbs do not have these, or have a single air screw up near the air horn.
Adjustable idle is important because you cruise on the idle cct at lower speeds. Lean idle [ because it cannot be adjusted ] makes the engine run hotter. Then, when you take off the engine is already 'hot' & you get pinging.
24* initial would definitely not be 'fine' with a 20* centri curve.