I just bought a 650 double pumper to replace the 3310 I had on before and it just blows it out of the water. After setting the carb up initially the only adjustments I've had to make were increasing the primary squirter size one step and moving the pump cam to the 2nd position. All the vacuum ports are nice on this carb too, im running pvc, brakes and full manifold vacuum advance. I'm amazed at the INSTANT, crisp throttle response it now has. I feel more power gains through the whole rpm range. I've mostly messed only with vacuum secondary carbs and edelbrocks, but now I know why holley double pumpers are king!

Can't wait to get to the track, ran 8.10 in the 1/8 last year with the 3310, hoping this carb can put me in the 7s!

 

I picked up 2 tenths in the quarter going from a 750 VS 3310 to a 650 DP 4777 on the 396. Most of it was in the 60'.

Wouldn't surprise me if you get into the 7's in the 1/8th.