Hey all I have a Holley Street Avenger 570 CFM on a FE390 I upgraded to a 50cc accelerator pump, I had to replace the carb so I just bought another 570 cfm Street avenger & all I did was transfer the 50cc pump over & used the same accelerator cam but the pump lever on the new carb only moves about a third of the way thru the whole travel of the throttle, on the old carb it moved thru the whole transition, I can't for the life of me see anything obvious different,I also have about a 1/4 in of movement left on the pump at full throttle & the adjustment screw is all the way out,, Thanks for your thoughts

 

Sounds like you may have put the "cam" in backwards or you used the wrong hole in the throttle arm. Did you use the pump arm for the 50cc pump?

 

I put them side by side this morning & found that the fuel bowl on the new carb has a difference of just over a 1/8th in difference in the height of the bowl where the accelerator pump mounts, this small difference is a big difference