My friend's new 700 has a 50 cc pump in the rear. What is the reason for this and how should I tune it compared to one with 30's front and rear? Its a race only engine.

Dragn70...the 700 carb has a leaner idle circuit on the secondary side compared to all other Holleys.....Usally also has no idle feed restriction in the back of the secondary metering block where you usally see it....instead its in the idle well in the metering block and cannot be changed real easily.....Thats the reason for the 50CC pump.....they do this to cover up a lean spot that occurs when the secondarys open.....keep it on there, it works well.........Jesse @ BIGS!!

Thanks for the info.