Idle to WOT issue

Combo is:
67 Dart
340 (400hp)
4 speed
3.55 gears

With my old 4777-4 (650 dp) I could ease out on the clutch and get the car rolling and then floor it and it would instantly break the tires loose. I have since bought a New quickfuel SS series 650 DP and it will not do it. With this carb I can ease out on the clutch and get it rolling, floor it, I get a brief pause, then the tires will start chirp and in finally the engine will start to rev and break the tires loose. What to check first?