Cliff's Quadrajet Parts and Rebuild Kits

General Category => Quadrajet Carb Talk and Tips => Topic started by: lightning boy on January 02, 2020, 11:52:27 AM

Title: Pump problems continued
Post by: lightning boy on January 02, 2020, 11:52:27 AM
When a 500HP pump cavitates it sounds like hundreds of 1/2" diameter ball bearings going thru the pump at high speed. I would guess a fuel pump like these would sound like BB's. Instead of just guessing when putting together a fuel system one should calculate the discharge head (what your pumping against) and if you cant figure out the NPSH you should at least measure it with a gauge on the suction side of the pump. Dont be surprised if this goes negative which is what you don't want. This is why cars do better with an in tank pump or a sumped tank. Not because there's more gas around it, its because its has more suction head available to it. Whatever you do should be in the way of reducing the friction on the suction side (adding to the suction head) this can be done by increasing the line size and eliminating bends and especially fuel filters. They will reduce the suction head too much. Hope this helps someone.