Inliners International Forums General Discussion Hi Performance High Performance Mechanical Fuel Pump - 250

Two more quick questions:

- What is the difference between the mechanical pump that has threaded inlets & outlets, and the pumps that have the cheesy 90-degree barb fitting?

- Most of the mechanical pumps for sale state an operating pressure of about 4psi, Holley states the minimum for a 390 is 5psi. Can someone expand on this please?

Thank you.