Re: Stewart Warner pumps
If you look carefully at some of the original car photos they did use a secondary regulator /filter unit. I have not found a need for this and use the SW regulator without any issues cranking 470HP on Webers.
What you do need to do is be very precise setting the pressure on both pumps exactly the same, this is the reason I believe they used a single regulator. If they had to replace a pump in a long distance race they would not need to worry about setting the pressure. When setting the pressure do not rely on a gauge, I use a piece of plastic tube taped to a graduated board and held near vertical at the carburettor fuel inlet and with the zero graduation at the same height as the fule inlet.
the height that the pump sends the fuel up the tube is then read off the graduated board. The height in feet X 0.434 = psi.
Finished assembling a pile of bits incl, mono, 302W on IDF's,ZF, 15" pin drive BRM.