[rsd66C20]

I'm not sure about what changed originally, or all of the changes you've made since,.....but it's conceivable that not enough advance and a lean carb could have caused the backfire during deceleration, and a general lack of power.

Sounds like richening up your mixture has helped out a bit (changing main jet from .98" to .100"). Out of interest, did you buy the tuning kit or just individual jets and metering rods? Sounds like possibly individual, if so, which metering rods? Even with the stock configuration on the 1405 (070 x 047), that will be much richer than the 1406 (075 x 047). Just so you know, the .070" is the diameter of the cruise part of the metering rod, that inserts through the middle of the jet. The .047" is the diameter of the power part of the metering rod. In this case, going to the stock 1405 configuration on the metering rod will richen the mixture even more. Just have to figure out the best combo. On my setup, I actually ended up in between the two with the #22 1457 (073 x 052).

I was interesting in your current timing was set at right now (12 initial)? What is the total timing and at what RPM did you reach it (of course without the vacuum advanced connected)?

One last thing, you may want to double check the Idle mixture settings, detailed on Page 11 of the Edelbrock manual. Good thing to reset with the other carb changes....and easy to do.

Good luck!!!