First, I didn't mean to cause a distraction on your thread. I have read all of these sort of threads in the archives, and was thrilled to see yours. Thanks for sharing the details of what you are doing. It really helps others such as myself to learn.
I do have a wideband and I think a reasonable understanding of carb theory. What I was trying to say was from what I understand the MAB will affect the main circuit activation point. I believe the IAB bleeds air into the idle well, with the idle well getting fuel from the main well via the IFR. As such I don't understand how the IAB could affect the main circuit activation. However, I'm still learning, and appreciate other thoughts on this. There are a bunch of knowledgable folks here, and I continue to gain the benefit of others posts.
In many ways, your are in a much better position than I since you need to add fuel, not take it away. I look forward to your results!
JimG,
I have read many of your posts on carb tuning in the archives, and appreciate your comments. Can you explain some more how the IAB change can affect the main circuit activation? I do have about 20" Hg during highway cruising, and believe even at 3K most of the fuel is still coming from the transition circuit. I didn't mean to get into the details of my setup on this thread (that seems like poor form!), but I would like to better understand your comments better.
How do you limit the transition circuit flow? As you noted, the main circuit is driven by flow. At 65MPH, you may need around 35HP?, which is not a lot of flow. Under these conditions, how can the transition circuit flow be reduced?
The only way I see is to have a greater throttle opening (lowering vacuum), but this will increase HP which will increase vehicle speed.
It seems like the transition is going to be providing most flow under light throttle, and the mains may be delivering just a little. Of course I can lean the transition via the IFR, which will get the cruise AFR into better shape but then the low end of the transition will be lean. I understand I need to get the best balance and shape of the AF flow on each circuit, it is just taking a lot of trial and error!
