I'm running a newly rebuilt downdraft 40 on a canon manifold. 123 distributor with tii tune, fresh coil, linkage is working well (and heim jointed), new fuel pump. When you really get into the throttle it falls on it's face as though there's a fuel delivery issue. lines are intact and flowing well. The carb is running 185 mains and airs, 60 idles, F2 emulsions tubes and 50 pump jet. The only thing I can think is a potential issue with the pickup in the tank. Unless the mechanical fuel pump simply can't keep up.
Any ideas on what could be the cause?