Changing 1/4" fuel line to 3/8"

[budlite28]

I have a 1939 Ford deluxe coupe that I am installing a sbc and need to increase the fuel line 3/8". I need suggestions on how to do it?

[Alaska Jim]

I would remove the old line in one piece if possible, then buy a roll of 3/8 steel line and then copy the original. may be tough getting the old one off and the new one in place in one piece with the body on, but it may be possible. I am not familiar with the 39-40 Fords.

[RKS.PA]

On my '39 Deluxe, I replaced the shot original fuel line with 8N braided stainless steel hose. I used AN fittings to plumb up my Holley 390 four barrel and I was very happy with the result.

Having said this, the cost compared to using 3/8 steel tubing was ridiculous!! Would I do it this way again.....probably not!!!

[Kube]

Originally Posted by budlite28

I have a 1939 Ford deluxe coupe that I am installing a sbc and need to increase the fuel line 3/8". I need suggestions on how to do it?

3/8"? Why? That's huge!

[51woodie]

There must be a retired fluids engineer on the Barn that could calculate the flow at the required PSI to tell you if the change in size is needed.

[aussie merc]

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simple DONT DO IT!!!!! why put a C--V in a ford ??? its not that im one eyed but if you want a C--V buy a C--V There must be plenty of Windsor's or Cleveland's out there

[paul2748]

3/8 is certainly overkill unless your going racing. 5/16 line, which is pretty much standard should do it.


There should (or may?) be adapters out there that go from 1/4 to 3/8 with the type of connections you need. But if your need adapters from 3/8 to 1/4, your no better off using the 3/8 line because at the end you still have a small hole.

[tubman]

Here's a little "real world" story. I had an acquaintance who drag raced a '57 Chevrolet Bel Aire two door hardtop with a 270 HP 283 (dual quads with a solid lifter camshaft). He was quite successful locally and won the SS/C class at the NHRA Nationals in (I think) 1961. The next year he was beaten several times by someone with a 210 Two door sedan with the same type engine. To keep competitive, he decided to install his engine an a newly purchased 150 business coupe, which was originally a 6 cylinder car. For the first year, he could not get the new car to match the E.T.'s and speeds of the Bel Aire. After a bunch of head scratchin' and research, he ascertained that the 6 cylinder cars came with a 5/16" fuel line, while the V8's had 3/8" line. A change of fuel lines brought the 150 to run times better than the Bel Aire. Unfortunately, the NHRA had juggled the stock classes in the interim, making the whole process moot.

Thus, while probably unnecessary for normal driving, a change to 3/8" fuel lines (as specified by Chevrolet from the factory) is probably the correct move. If 5/16" restricted performance, 1/4" would hurt it even more. If you are going to go to the trouble of replacing the fuel line, I think it would be a wise move to go to the size determined best by The General. And if the engine is a 350 (or maybe even a 383 or 400), the size change is probably mandatory.

Please note : This is NOT an endorsement for installing Chevrolet engines in early Fords; just knowledge gained from real racing experience.

[Bored&Stroked]

I would use 3/8" NiCopp line instead of a standard steel line - you'll find that you can much more easily bend/form it to fit an existing chassis where you're not pulling the body and probably need to work in various angles/bends to get it to fit right.

You'll need to have a tube flaring tool and make sure you buy the correct inverted flare tube ends (Jeg's has them as well).

Here is a link:

https://www.jegs.com/i/JEGS/555/635806/10002/-1

[bobH]

Fer whatever it's worth.... I have a 69 pickup that came factory equipped with a 350, and 3/8 fuel lines. I've had it over 50 years, and in its younger days I worked it pretty hard, hauling a camper and towing a jeep all over the western states. That 3/8 fuel line was (and is) never enough. Whenever I get into it, with a load, in the mountains, where I'm into it for any distance at all, I run out of fuel. (BTW, I have a gage that monitors fuel pressure- at the carb inlet.) To deal with this, Many years ago (almost 50) I added a booster pump, which I can turn on when I see fuel pressure dropping to zero. Bottom line, I believe 3/8 line is needed if you're going to be pressing it -- like for racing, or like in my case, hauling heavy loads in the mountains. BTW, like above post, not endorsing sbc's, just trying to relate experience.

[Newc]

I am doing this also, but the original gas tank may have a 1/4" out fitting only? Check the tank outlet first. Newc

[budlite28]

That's the problem. Once I pulled the 1/4" compression fitting, there is a 1/4" restriction going into the tank. Since I'm installing a 383 stroker motor I need a larger fuel line. Other than welding 3/8" bung on the tank not sure what else I can do

[Pete]

Originally Posted by budlite28

That's the problem. Once I pulled the 1/4" compression fitting, there is a 1/4" restriction going into the tank. Since I'm installing a 383 stroker motor I need a larger fuel line. Other than welding 3/8" bung on the tank not sure what else I can do

It would almost be a sure bet that seeing as you are going to a 383 right off the bat that eventually that won't be enough and you will want a big block so as long as you will have to weld a new bung in the tank, go straight to 1/2 inch. While you are at it put a 3/8 bung in the top of the tank also. This will be for a pressure regulator return line when you discover that dead head regulators do not work on perfomance engines. Plumb in a 3/8 line from engine compartment to this fitting while you are doing fuel lines. You can block it off for now.

[TJ]

Put a poly gas tank in it which has the 3/8" fuel pickup line. Some of the new steel replacement tanks may also have the 3/8 line. The poly tank also has the advantage of 2 extra gallon capacity. Another option is to install a later model sending unit with a built-in pickup line into you existing tank. You will then have to use a gauge that matches the sender. Classic Instruments and maybe others makes the sending unit with the built-in line. You will also have to buy the adapter to go from your stock tank to the later sender.

[Yoyodyne]

Originally Posted by Bored&Stroked

I would use 3/8" NiCopp line instead of a standard steel line -

+1, it's way easier to work with. I'm also using it around the machine shop for things I used to use copper tubing for because it's tougher than copper and nicer to work with than steel. If you carefully unroll a coil across the top of a workbench it comes out straight enough for 20' away.

Originally Posted by Pete

It would almost be a sure bet that seeing as you are going to a 383 right off the bat that eventually that won't be enough and you will want a big block so as long as you will have to weld a new bung in the tank, go straight to 1/2 inch. While you are at it put a 3/8 bung in the top of the tank also. This will be for a pressure regulator return line when you discover that dead head regulators do not work on perfomance engines. Plumb in a 3/8 line from engine compartment to this fitting while you are doing fuel lines. You can block it off for now.

^^^^What he said. 3/8" can be marginal these days. Bypass regulators are much more consistent and freer flowing. Plus If you ever choose to run old carbs like Strombergs that need low pressure, the bypass will save the day when trying to maintain single digit pressure. And more - If you step up to EFI you'll need the return line.