Sorry to disagree,but ive got copper line betweem pump and carb for 20 yrs never any trouble.Thats what the flex line is for [vibrations] between engine and frame.Engine,carb,carb line and pump all move together there is no movement to them there all bolted to the engine.Only my 20 yrs experiance.ken ct.This steel copper plated line is strickly for the show trophy people who never drive them anywhere but on an off the boxes they carry them around in.