[FWB]

personally i don't trust holley with anything, but that aside, the 3\8 is definitely too small, 4 and 6 cly street cars have 3\8 line, a small block has a 3\8 line. if you kept the rpms down to street levels of lets say 4500 you may never have an issue. but the 750, and i'm guessing here may be jetted in the 72 to 78 primary and 80 to 88 secondary needs fuel, if you feel the 3\8 will be fine then try it by all means. bypass the mechanical pump, i would bet the car will run better. watch for flooding with the 7 psi. if you still have a issue with performance then consider the 1\2 line. just my opinion, i've been messing with these motors since 1978, a 3\8 line came factory, and on the dragstrip, it felt like you were hitting a brick wall in high gear when you just plain ran out of fuel. we ran the holley blue pumps. and even in that environment 6 to 6.5 fuel pressure. switched to 1\2 inch line and it would pull the whole way.


if you retain the 3\8 up by the manifold that will probably be fine, its the volume from the rear to the front, the 3\8 probably travels rearward from the front anyway so inertia will help there.