I just went through the full process of getting my car to stop a light bog off the line. Many things were suggested (thread is here in the FE Talk forum, "Accelerator Pump tuning"). In the end, careful idle tuning plus a more aggressive accelerator pump cam did it. A change from 15+21 timing to 18+18 timing didn't hurt, may have helped.
Jets and power valves have almost nothing to do with an off-idle bog. The relatively cheap and simple progression is:
- Bigger accelerator pump squirter - go up two sizes, twice, to see if it helps;
- More initial timing - go to an 18* stop and 18-20* initial;
- More aggressive accel pump cam - I went from pink to blue and it made more diff than anything else;
- Make sure the idle is set correctly. In my case, my "perfect" tune using vacuum was too lean and I opened everything up another quarter turn for noticeable improvements.
In the end your power valves may be too high - the rule is idle vacuum / 2 + 0.5, use nearest next-higher value. For 14 inches, that would be 7.5, so you're a little sluggish on the added fuel... but that only applies under heavy load and a lot more throttle than normal off the line launches.
I'd bet 37 or 41 squirters will show some improvement, given that it's such a small primary carb. 37 squirters and an orange or blue cam, and I bet you're most of the way there. The timing change will help, too... FE's love advance.