I live in the Raleigh area, a bit over an hour from the VA border but east of you.
I'm certainly in the battle for taming a high HP engine for regular street use. Your description is perfect. My situation is even further complicated by use of a stock 440 torque converter for the time being (started with a MP 175K converter behind my engine, but it was too loose for my taste during normal street driving), and use of a single plane intake manifold (M1) which really complicates the idle situation (more on that in a moment).
I found your comment on spreadbore carbs interesting. Obviously some stock racers can get great performance with ones like the Thermoquad but from a high performance standpoint, I wonder about potential fuel distribution issues with the biased flow in such a carb (ie cylinders 1&2 running leaner). The smaller primaries would be a great solution for my challenges though. Clearly a fuel injection setup would be easier to tune for the various conditions for a street/strip vehicle, but that is not in my budget at the moment! Besides I still feel my carb should be able to work better than it currently is, and I don't overly mind the challenge.
So, back to the theory. Your recommendation to use the smallest IFR and largest IAB possible makes a lot of sense, along with starting the mains early to overlap the transition circuit to cover the lean area. I have already explored that path a bit, and got to a state where I could not cure an off-idle (1200-1300) lean miss and had to come back up on the IFR some. I should probably invest more effort in this direction though but the cam timing certainly presents low RPM mixture challenges. My thinking is that the large IAB was delaying the start of the transition circuit.
I had heard mention of transition slot restrictors before, but don't have a good appreciation of the way to implement this. Also, I can see that it would be fraught with potential problems. Can you explain some more about this?
Currently I have been considering two different directions. One, as I mentioned, was to try to delay the main activation some. However, your comments are reinforcing my thoughts that the majority of the fuel is coming from the transition circuit, and as such delaying the mains would have a muted impact.
The other direction I am considering is switching to a dual plane intake (EBrock RPM). Many seem to be making good power with this. I believe this may help in two ways. First, it should improve the idle vacuum, which hopefully will allow a slightly leaner mixture while still maintaining a stable idle in drive. Second, because each cylinder would only see 1 barrel of primary, it seems to me that the throttle opening position would be increased relative to my current setup, with the benefit of lowering the highway cruise vacuum level, which should reduce the draw on the transition circuit. Would you agree that I could expect both of these benefits from a DP?
