[zach69elcamino]

Someone told me that the stock (5/16) fuel line in my El Camino won't supply enough fuel at high RPM for my 454 with a 780 holley (about) 500 horse, is this correct? All help is greatly appreciated!

 

[Chevyobsessed]

You'll need more fuel to feed 500 HP than what 5/16th's will supply. You need 3/8ths and even with 3/8ths, you still need a well thought out fuel system; adequate pump, filter, proper bends, tank venting, etc.

 

[sschevellefan]

Someone told me that the stock (5/16) fuel line in my El Camino won't supply enough fuel at high RPM for my 454 with a 780 holley (about) 500 horse, is this correct? All help is greatly appreciated!

Well, yes and no. My 65 has a 427 with about 400-420hp and it still has a 5/16 line and Ive ran it up to 6200-6300 several times with no indication of it starving. Some, many have posted about fuel starvation on their cars with a bbc and 5/16 line. You will have the occasional success story like mine but most will agree its on the small side. The 4bbl cars got the 3/8 line. Im actually going to convert mine to a 1/2 line over the winter.

 

[1966_L78]

Well, yes and no. My 65 has a 427 with about 400-420hp and it still has a 5/16 line and Ive ran it up to 6200-6300 several times with no indication of it starving. Some, many have posted about fuel starvation on their cars with a bbc and 5/16 line. You will have the occasional success story like mine but most will agree its on the small side. The 4bbl cars got the 3/8 line. Im actually going to convert mine to a 1/2 line over the winter.

:thumbsup:

It all depends on HOW you are using it... But you have to remember that you carburetor holds some fuel alread, and the 5/16 line will still supply some fuel, not like its completely blocked off. 5/16" fuel line has about 70% of the cross-sectional area compared to 3/8" line...


But lets say your cruising at 120 MPH and get 5 MPG in doing so... Thats about 24 gal/hour or 0.40 gallons per minute...

Now if you figure this is drag racing, lets assume you are at full-throttle for 13-seconds... Thats 0.087 gallons, or about 11 ounces used in that 13-second run...

I don't know how much fuel the carb bowls hold, but I'd guess about 6-8 ounces total?

So you would run the carb dry on a quarter mile run, IF you had no more fuel... But you still have some fuel coming in from the 5/16" line, but it might be close...

So sure, IF you are racing the car, or really beating on it hard for extended periods, then you probably will need a bigger fuel line... But just romping on it now and then, going through a few gears but then letting off... Then you might be okay...


Also remember that some people that complain of fuel starvation with the 5/16" line might also be experiencing a partially clogged in-tank filter, etc.

 

[Chevyobsessed]

I can't even believe I'm outnumbered arguing that 5/16" fuel line is too small for a 500 HP BBC.

 

[sschevellefan]

I can't even believe I'm outnumbered arguing that 5/16" fuel line is too small for a 500 HP BBC.

No your not alone. I agree its too small but untill he can upgrade the car will still run. Mine is doing ok but it could be running out of fuel on the top end but I have only ran it up to 6200rpms in 1st and 2nd gear. Mine is getting upgraded this winter, hopefully the OP will upgrade his too