Look at the Holley site:
http://www.holley.com/0-80509-1.asp
and look at the 4150 HP series carb. Double Pumper, mechanical secondary with a metering block, accel pump and power valve on both the primary and secondary sides. Part #: 0-80509-1
You can't see the second pump lever on the pic that Sal posted because it's on the other side of the carb and the picture doesn't show it.