I'm selecting a fuel pump (mech) for my motor. Based on my carb (850), cu in. (454) and rpm range (6500) my motor math tells me I'll be flowing at least 726 cfm at 85% efficiency. Using these figures I will need a fuel pump that will need to flow about 45 gpm.
My question is this: If I get a fuel pump that flows 70 gpm, what happens to the extra volume of 25gpm (70-45) that the carb obviously doesn't need. Are fuel pumps built with relief valves? Or does the carb only take what it needs? Will the pump overpressurize causing leaks if the volume differential is too great? The lower pressure pumps I'm looking at (6-8psi) do not require regulators.