My Zenith 801 is going together, wings are on and I ran it with the propeller on for the first time last week. I added pre-filters as recommended to the fuel lines going to the header tank and started my fuel flow tests tonight.
Initially I put on WIX filters, but then found better ones: Golan Products. These are really nice filters, aluminum bodies with a washable stainless steel element. You can find them at Dennis Kirk and Amazon. I bought mine directly from the factory, they had 3/8" inlets, I couldn't find the 3/8" filters anywhere else.
I did a fuel flow test with each one.
In one minute, the WIX filter allowed .56 gallons of fuel to flow through it, more than enough for the 180 hp engine which should have .34 to .41 gallons per minute according to Advisory Circular 90-89B.
The Golan filter was exactly double, 1.12 gallons per minute.
The header tank is behind the rear seat, I had to cut out a hole in the bottom of the fuselage and hammered out a teardrop fairing for it. There is an access for the fuel drain.
These are 3/8" hoses going to the header tank. The pressurized fuel is through a solid 5/16" stainless steel tube going under the fuselage to the engine, I wanted to minimize any pressurized fuel lines inside the fuselage.