I have run it a couple of year with both an 4781 DP and a Pro form 850 DP and I also have an 3310 on the self... but no on that one.
It run cleaner and has more crisp throttle response with the P/F 850 but the 4781 was overall faster on the track, but it running pig rich on part throttle when is tuned for 12.5 A/F at wot.
P/F 850 is 1.75 X 1.40" If I remember correct and the 4781 is 1.75 x 1.56" venturi. I thinking it may want more cfm because it was faster with the "bigger" 4781? Well, do I need a bigger carb?
Okay, that extra information helps. Yes, the car would probably be faster with a bigger carb but your original post said it was a weekend cruiser and not a race car. So which is it?
For a weekend cruiser just rebuild the 3310 and go cruising. If you are looking for the faster carb at the track then get one of your other carbs tuned up and use them. I don't see any reason to buy another carb when you already have a few on the shelf.
If the 4781 was rich at part throttle when 12.5 at WOT then you probably made the very common mistake of using the main jets to tune for WOT. You should use the main jets to tune for cruise and then add extra fuel for WOT with the power valve circuit.
Or just sell the three carbs you have and use the money to buy a Super Sniper EFI kit. Then you'll have the correct air fuel ratio from idle to WOT and you'll have built in data logging and you'll be able to control your ignition timing with the computer.
