Carb Timing Question, Backfiring... Options

[yarin]

I'm trying to work on the timing on my car. I bought a Sears Induction Advance timing light and i'm going based on Pelican's tech articles. Basically the car backfires like crazy over 3k rpm at any decent load. I hooked up the light, i think i see the major 34deg mark on the fan.. is this the wide fan blade? Do I set the timing light to 27 degrees at 3k rpm and line up the large fan blade with the mark on the housing?

Anyhow, i changed the timing around a bit and it still backfires like crazy out the exhaust. It also huffs on the intake side here and there.

I don't have any electronics to set the dwell.

This problem came up after two autocrosses. Any ideas? Fresh plugs, cap, rotor and wires already done.

This is my first time really getting into carbs so pardon my ignorance but I can't seem to find the "vacuum advance line"? Where would it come from and where should it connect to? Thanks!