I got you on this one MikeM since I just went through my 440 six pack set up (for the umptienth time) and now I think I've got a good handle on it....thanks to guys here and over at FBBO.

Anway....

1. Your power valve is correct for your vacuum. I'm also running a 4.5 with 12" vacuum (I could go to a 5.5 since there's a teeny-tiny hesitation just off idle during acceleration).

2. Front/Rear springs should be the same.... the front/rear carbs are connected via the mechanical linkage anyway.

3. A "bog" is because the front/rear are opening too fast vs. the accelerator pump squirt in the center carb. Either put in stiffer/slower springs or increase the center carb accelerator pump squirt with a bigger pump cam, larger squirter + bigger pump cam, or change the existing white pump cam between "hole #1" and "hole #2". I can't remember which hole gives a bigger squirt.

4. Many people tell you to increase the center carb's jets & do a bunch of modifications to idle circuits, air bleeds, etc. I STRONGLY suggest that you start with the carbs completely stock & work from there. I un-did a bunch of these modifications I'd done in the past on my six pack and the car is MUCH faster with the carbs almost bone stock. I'm running #61 main jets at the suggestion of "Six Packs to Go" (I think that's their name) out in Albequerque, New Mexico. He's raced six packs for MANY years and knows his stuff. The only REAL way to be sure is to use oxygen sensors or get the car tuned on a dyno where they can measure your fuel mixture.... or track time.

5. Your cold stalling issue is definitely because you're not running the choke.