All in by 2500 is for race cars that have big TCs, and two modes of operation; namely idle and WOT.And they don't run vacuum advance.
A streeter has to satisfy a bazzilion different operating parameters, not the least of which is a whole lotta time spent at under 3500 rpm. What is the point of sacrificing driveability below 3500 in the name of "I gotta race Distributor", or some such story. If you don't have a 3500Plus TC than you can't have all in before 3500, plain and simple. Well you can but it totally messes up part throttle, and economy.
See at part throttle and steady state, and lower rpms (sub 3500 say), the engine could be wanting 30 or 40 or occasionally 50 degrees of timing. But as soon as the throttle begins to tip in some of that has to drop out. And the faster you tip it in, or the heavier the loading, the quicker it has to drop out. So if your centrifugal timing is already walking a thin line to detonation, the trickier it will be to to satisfy the cruise and PT requirements.
Since you rarely ask for full power below 3500, and a 340/360 usually has more than enough cubes to spin-up street-tires even several degrees short of optimum timing,it seems to me somewhat foolish to completely throw away the tune in this most used area.
So as a compromise,recurve your dizzy to provide 34* at 3400, and idle timing of 12 to 14. Then install the biggest Vcan you can get (I have found none bigger than 22*). And start tuning that bad boy. The max timing can be controlled by shimming the arm. The rate of advance can be controlled by the little screw inside the hose-nipple.Then when you think you got it all dialed in pretty good; add 2* more initial, to get 36* at 3400, and start over.....And when you get that working, recurve it again to get 36* at 3200 or 3000 if you are feeling lucky....
As the engine starts to get the right PT timing it will be possible to start leaning out the low-speed circuits.
This is the road to fuel economy, cool running, and a torquey bottom end;free from detonation.
But while all this is going on, the engine running temperature has to be stable. If the temp is dancing around it will be impossible to work something out. Impossible. So if your carb is still sucking hot underhood air, don't even bother beginning a tune. You are just cooking the fuel, and cooking the air. And the inlet air temp will be all over the place. And the air-density will be dancing worse.
