Base timing. Really ?

Glad i stumbled onto this post before i made a new one. On my 440 with 284/484 cam installed 2 degrees advance, 9.4:1 compression, street dominator intake, 3000stall convertor in a 1972 dart, I have the electronic ignition with an FBO limiter plate in it and if i remember right, 1 spring in the distributor. Timing is at 20 initial and 34 total. The timing is all in by 2800. I THINK too light of a spring is the issue and after reading all this i really think it is the issue, but when laying into the throttle at lower RPM's, like under 3500 i guess, it detonates a little, but i dont hear it if i lay into it when the rpm is higher..Thoughts?