I ran 2 vac sec 600 holley's on a 350 bracket mtr and mine were tied together and I would say that is a must do . Also was not happy till I removed the power valves. Later J.Smith 4621 racing
besides pairing the vac. together, did you use progressive linkage or have them operating together ? some tell me that the progressive linkage will lean out the rear cyl's. what's is everyone's thought.