Will try and keep it simple. Got my newly rebuilt 360 running great with the Holley t/a 670 except for one thing...... If I mash the accel. to the floor or on a steep grade my vacuum gauge will drop to zero and the secondaries on the 4 barrel carb. will not open. This gives me a "flat" spot in my power curve. As long as I have at least 1Hg. of vacuum showing (lighter foot on the pedal) the secondaries stay open and the engine continues to build power.

I have nothing to compare my vacuum gauge readings while driving to. My vacuum reads 14Hg. at 850rpm. I could really use some ideas about this delima. I am already using a very light spring in the secondaries, although I could still go two springs lighter if necessary.