Changing fuel line diameters

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Moparmal

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I hope this is not confusing -

I've noticed on a lot of forums - guys run a 5/16 fuel line from the tank to the electric pump, then 3/8 under body to the filter, then .5" to the carb - Or some other "combination" of fuel line diameters.

Is there any benefit in doing this? Or would it be better just going 3/8 all the way through?
 
I think it depends on how much fuel your carb is using. If it is using a lot of fuel and the pressure is not consistent bigger lines and a pump that flows more will help.
 
You never want to go small line to big line. ie (5/16 to 3/8 ).

Going from the tank to the pump with 3/8" then from the pump to the carb with 5/16 is perfectly acceptable. This is actually a old trick back in the day when cars came with 5/16 line all the way through.Even big block cars came with 5/16 fuel line.

Is 3/8 all the way through better ? Yes.
 
So I guess the "staggered" fuel lines are just away of gaining a little extra volume.

I'm going to run 3/8 all the way - who has the best price on a 3/8 sneder/pick up?
 
Vans auto has 1/2" and 3/8" pickup tubes for $75 I believe,
 
Johnny Dart:correct. I think you will find that no matter what kind of pump you are dealing with, the inlet is always at least as large as the outlet and often a little larger.
 
Moparmal said:
So I guess the "staggered" fuel lines are just away of gaining a little extra volume.

I'm going to run 3/8 all the way - who has the best price on a 3/8 sneder/pick up?
Click to expand...

Keep in mind that a stock mechanical fuel pump comes with "fixed" 5/16 fuel barbs.

To go to a 3/8 fuel line you will have to get a aftermarket fuel pump with screw in fittings. Such as Carter,Holley,Edelbrock.

I picked up a 3/8 sender off the Bay.
 
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