Quote Originally Posted by Itoldyouso View Post
Most important thing is to mount a fuel filter BEFORE the fuel pump. Holley pumps do not like even a spec of dirt. Get one that has a replaceable cartridge (not one of those inline ones) and mount it right before the pump and after the tank.
Don
Don,
This is one that you and I disagree on. In support of my analysis of the system hydraulics, Edelbrock instructs that it is important for the filter to be AFTER the pump. From their ProFlow XT instructions, Fuel System Installation pages:
7. Mount the fuel pump between the tank and the fuel filter as low and as close to the fuel tank as possible. The pump is directional. Electrical connectors should face the front of vehicle. The fuel pump needs to be at or below the bottom of the fuel tank.
8. Mount the fuel filter between the fuel pump and the engine.
This is their brochure for the whole picture - http://www.edelbrock.com/automotive_.../3000/3520.pdf
As for the hydraulics, the pump is designed for a positive suction head and is not designed to "pick up" the fuel. By installing the filter in the suction line you are imposing pressure drop in that line that is equivalent to raising the pump several inches. This means that as your tank level falls you will reach a point where the pump is operating off design, and as your filter ages you may well be negative on pump suction witih a full tank. Cleanliness is critical, and if you read their instructions they say to have an old tank "professionally cleaned".

For me, I rely on the inlet sock filter in the tank to protect the pump, and I install the filter downstream of the pump where it eats away a small amount of pump head (pressure) as it ages, but keeps the pump primed at all times leading to longer pump life. I respect the alternate position on this, and I know that there are many who prefer to filter the pump inlet but the physics don't work for me.