Hi Mike
As Wiggles said, “It is very difficult to determine a “base setting,” given the vast number of settings”.
So to your question “But from your mains & air correct it’s possible they might provide more top end pull?” I have no idea.
I found the specs for the additional progression hole online in a article called “Weber Wisdom” and other than the general agreement on the 152’s and the additional progression hole, no two configurations were identical. And if you look at Hammill etc. again just a baseline suggestion.
The Webers are on a Rob Beere engine and I sent the carbs to Rob and he set them up on an engine dyno. Full race cam and larger headers with redline at 6000 (though have the rev limiter on 5500).
No O2 meter so I have no way of knowing what is happening on the main circuit other than seat of the pants. As it mostly runs on the idle circuit I am ignoring it and I haven’t touched the main circuit fuel or air corrector from that time.
When I added the additional progression hole I had to play with the idle jets but other than that nothing. The change made a significant difference to improving the fuel consumption. I don’t have a fuel gauge (Tempero D-Type) so on a long run you are working on the range of a full tank. Of course if you are pushing it all bets are off!
I have on the to do list to measure the vacuum on each choke just to see how balanced they are but they run pretty well so more of an academic exercise than solving a problem.
Regards
Keith