Fuel line size unforeseen problems

I messed up and at a swap meet ordered a new fuel line for my 53 Pontiac. They had two sizes listed 5/16 and 3/8. I thought the smaller size must be for the I line 6 and the larger for the inline 8. Well it delivered today and is very nice. But my turns out to be 5/16 and I bought the 3/8. Looking at the set I can make it work but with an origional fuel pump will the larger line cause any unforeseen problems? Will the pump pull the fuel properly? Will it supply too much fuel? Thanks for your help

The amount of fuel delivered is governed by the float valve in the carburetor. As long as you give it more than enough, no problem.

The larger diameter pipe will cause less head loss in the fuel line, so the low pressure side of the pump should be able to bring more fuel per stroke. But it will only bring what is required to replace that being sent.

If the fuel line loses prime, the larger diameter pipe will mean a larger volume of air to pump out to reduce the pressure sufficiently to pull fuel. Thus it might take longer to fetch fuel after a long lay-off. Fuel pumps are normally mounted low down, near tank level, so the low pressure required should not change.

So, no problem, as long as the system is in good condition and doesn't lose prime.

It won't make any difference. It won't help, but it won't hurt either.

The only car I know that came from the factory with 3/8 fuel line was the Chrysler hemi muscle cars of the sixties. Even the 440s got enough gas thru a 5/16 line.

The only problem I foresee is the fittings on the larger line will not fit your tank, fuel pump and carb.

Thanks everbody for your help. This is good news.

I had a cooling problem on one of the race cars that went away when I increased the fuel line size.

So if the engine is demanding alot of fuel and cant get it it will run out lean and overheat. (That one was a head scratcher).

This was an alcohol injected engine and it used a BUNCH of fuel. (and went really fast) In a 100 lap race the unloading of the fuel would change the handleing of the car as it was getting lighter in the rear as the race went on.

Fun Stuff !!

It is possible that, if the car were prone to vapor lock issues in very hot city driving conditions (say 90 degrees plus), the large line MIGHT make this condition worse.

Other than that, no negative issues.

Jon.