Abstract: A header and a pump end for a cryogenic pump are provided for efficient liquid pumping operation. The header directs supplied liquid into a sump and gas into a freeboard. The liquid in the header can be distributed along the header and decanted over a weir to the sump, the liquid being drawn from the sump and up through the vessel to the pump end. Gas in the freeboard is collected for venting or return to the liquid source. Pump head plunger stroke can be lengthened and operated at slower stroke rates using a large cross-sectional area intake and discharge valves. Plunger seals, supported as a seal pack in a sleeve, are field installable over the plunger. A plunger to drive shim arrangement permits filed adjustment of the stroke.