Fuel Line

[bobs66440]

I'm not sure if this is the correct category, but it involves the frame, sooo...

I'm getting ready to run the fuel line from the tank to the engine and am looking for some ideas regarding if I should use hard line, rubber or braided. It's a relatively short distance, so I'm tempted to run rubber or braided, but prefer hard line. I'm using a barbed fitting on a shut-off valve at the tank to the fuel pump (SBC), so my initial thought is to use hard line then a short rubber line to connect the tank and fuel pump on each end. Is 5/16" big enough or should I go with 3/8"?

 

[john dioli]

I always use 3/8 hard line with rubber just where needed for barb fittings .
john

 

[Screaming Metal]

Well, heres a formula I use for single lines.... 1/16 for lawnmowers, 1/8 for big lawnmowers/ motorcycles, 1/4 for stock car fuel-lines and large bikes, 5/16 for up to 400 horses, 3/8 for up to 525 horses, 7/16 for 700 horses, and 1/2 for anything over 800 horses.
On the hard lines, run hardline or braided from the back to the front, using rubber to connect from pumps/filter to the line, then up front rubber to mech. pump/log/reg./carb....
Alum fuel lines can be breached too easily for my liking (I actually dropped a screwdriver once, puncturing a alum. fuel line), but copper/brass/SS will suffice for strength, durability, longevity....Always mount fuel lines either thru the frame rail or up to the inside where things can't hit the line.
Rubber is a fast and easy way to run line....but its not a strong, durable or bulletproof way to get fuel from point A to point B.
I have seen several deep cuts on low mounted rubber lines the past 10 years in street cars. Running high pressure pumps with hoses with deep cuts is a way to burn down a car while going down the road. Its best to be safe than sorry....

5/16 is plenty good for a healthy SBC....

 

[Golly]

Definetly as much hard line as practical ,just for durability, eg: rocks or debris flying under the car. And good quality hose barbs etc. Do not use any 90 degree fittings, and I would go 3/8" Just my thoughts.

 

[ellis8500]

When my neighbor, who owns a Mercedes repair shop, told me that Mercedes uses rubber fuel line, I tosses the coiled aluminum aside and went with the flex line. With a carb rated fuel pump, 7 psi, line pressure is not an issue. Even though there is some hard line in most cars, much of the line is still flex line. In the factory it's easier to install a preformed hard line than it is to install a long run of flex line.

 

[fordsbyjay]

I have 1/2" aluminum line on 3 of my cars. I have never developed a leak in 20+ years. The line should not be exposed anywhere where it can get damaged in the first place. Saying that, I realize that there is always the potential it could get punctured because it is softer. I have just never seen it (one of those theory vs reality things). If you only need 3/8" I would use steel brake line for as much of it as you can. With this new ethanol gasoline it eats rubber so I try to minimize rubber as much as I can. As far as Mercedes using rubber lines. I doubt they are the same cheap quality that you are going to be buying at Autozone so that is not a good comparison.
You should be able to run hard line from the tank all the way to the firewall where you need a short piece to the carb for flexibility. I use a quality push loc steel braided line for this. We are talking less than 18" and this is definitely not the place you want to develop a leak.

 

[EX JUNK]

These pictures show how I did my fuel line. The first shot shows the flex line to the fuel filter.



This is shows from the filter towards the fuel pump with 3/8" hard line.



This depicts the connection from the solid 3/8" line to the fuel pump with a piece of flex line.



I'm a firm believer in the "KISS" principle which is "Keep It Simple Stupid".

Jim

 

[Screaming Metal]

I always enjoy seeing Ex Junks T! Anybody out there, if you want to run say 3/8s rubber fuel line to upfront, cover it with some split loom or some sort of plastic sheathing, run it out of the way and anchor it with P-clamps or with wire ties.
Don't get me wrong here, the 3/8s soft line is durable enough, but, if put into the situation of rocks hitting it or other road debris being flung up by wheels and tires, I've had several leaks, mostly from gravel roads and or rough roads having crap slung up by the tires. Over the past 10 years, I've had 3 instances....therefore I run hardline now, but thats me. Do what you want.
3 cars and alot of years, driving with alum. line, no problems, good. All it takes is one sharp rock....
I won't trust it though, unless I have splitloom over it to protect it.
Wanna run a hard line, get some steel, copper, SS line and your benders and bend it up, and you know it'll be there 20 years down the road.
Just my 2 Pecos..............................

 

[bobs66440]

Thanks for the replies! I think I will go the steel hard line route with rubber on the ends as suggested. Thanks!

 

[Swampdog]

EX Junk,
In the middle picture you have a transmission oil cooler. I just installed a higher stall torque converter and I am contemplating what kind of cooler to install. How does that work? You route the line coming out of the transmission thru the cooler then to the radiator or what. Does that suffice? If I go with a fan cooled cooler I will have to change my alternator (presently have a 65 Amp) to a 100 or 150 Amp. Everything is $200 more dollars.

 

[EX JUNK]

EX Junk,
In the middle picture you have a transmission oil cooler. I just installed a higher stall torque converter and I am contemplating what kind of cooler to install. How does that work? You route the line coming out of the transmission thru the cooler then to the radiator or what. Does that suffice? If I go with a fan cooled cooler I will have to change my alternator (presently have a 65 Amp) to a 100 or 150 Amp. Everything is $200 more dollars.

I do not use the trans cooler that is on the radiator. The cooler shown is all that I use and have had no problems in about 20K miles.

Jim

 

[Swampdog]

Thanks Jim.

 

[BOB S]

First of all
I get such a kick reading what you guys post teasing each other it's really a friendly site and everybody gets along just as least what I can see.
I have only one suggestion if you don't mind
I would not use the mechanical fuel pump
I prefer electric fuel pump's to me it just looks cleaner not to see the mechanical fuel pump
just from the pictures you have posted that I have seen you are doing a spectacular job keep up the good work can't wait to see it done

bob

 

[T-Test]

First of all
I get such a kick reading what you guys post teasing each other it's really a friendly site and everybody gets along just as least what I can see.
I have only one suggestion if you don't mind
I would not use the mechanical fuel pump
I prefer electric fuel pump's to me it just looks cleaner not to see the mechanical fuel pump
just from the pictures you have posted that I have seen you are doing a spectacular job keep up the good work can't wait to see it done

Mechanical pumps are more reliable than electric IMHO. And you can get them anywhere, just in case it fails. Custom parts are [to me] for garage keepers/drag racer's and usually don't see any real road time. Do you remember the early MBR shows where the cars didn't even have to run? They pushed them out of the trailers and into the buildings. Not my thing at all. If it is worthy of MBR or any award, it should prove to be road worthy by doing a road trip of 50+ miles without failure. Off subject, sorry---SM's advice about fuel line size is great, but IMHO 3/8 fuel line will supply enough fuel to any engine up to 1000 HP with a blower as long as the carb/carbs can act as they should. Hard line is best for durability and safety with flex/rubber/braided or whatever between pump/filters/etc SAFE is far more acceptable than looks or performance IMHO/ which sometimes [opinion] aint worth saying at all .

bob

 

[EX JUNK]

You have stated my sentiments exactly, Bob.

Jim

 

[T-Test]

Post #14 must not have been important. I forgot to copy before posting and it never made to the board. Must have timed out.

 

[EX JUNK]

Post #14 must not have been important. I forgot to copy before posting and it never made to the board. Must have timed out.

Simply click on the shaded portion at the end of the quoted part from Bob S. and you'll see your post. That was why I was able to answer like I did.

Jim

P.S. here is what you said in post 14:

Mechanical pumps are more reliable than electric IMHO. And you can get them anywhere, just in case it fails. Custom parts are [to me] for garage keepers/drag racer's and usually don't see any real road time. Do you remember the early MBR shows where the cars didn't even have to run? They pushed them out of the trailers and into the buildings. Not my thing at all. If it is worthy of MBR or any award, it should prove to be road worthy by doing a road trip of 50+ miles without failure. Off subject, sorry---SM's advice about fuel line size is great, but IMHO 3/8 fuel line will supply enough fuel to any engine up to 1000 HP with a blower as long as the carb/carbs can act as they should. Hard line is best for durability and safety with flex/rubber/braided or whatever between pump/filters/etc SAFE is far more acceptable than looks or performance IMHO/ which sometimes [opinion] aint worth saying at all .

bob

 

[Screaming Metal]

Post #14 must not have been important. I forgot to copy before posting and it never made to the board. Must have timed out.

Yea...I get that alot....evidently I type slow...., or it might be my constantly being interrupted by folks....while I'm trying to post.
I gotta go get my sausage/egg bisquit and my coffee....I feel the coffee rush easing up!

 

[Screaming Metal]

Yea...I get that alot....evidently I type slow...., or it might be my constantly being interrupted by folks....while I'm trying to post.
I gotta go get my sausage/egg bisquit and my coffee....I feel the coffee rush easing up!
Really and truely, a mechanical pump is hard to beat. I just dislike the rubbing on the cam, it just grates on my nerves since most things I build are rollers.
With the way the arm is shaped, the way its contoured, and its hardness, it puts a minimum on metal into the oil, wear wise. The only reason why I don't run them is because I have to prime the systems when I'm working on things, without turning the motor over.
Also, should a diaphram let go, you'll dilute your crankcase oil with gas.... or pump it out on the ground. If going down the road, it'll pour onto a hot header....
I just don't use them for that fact, the major one being I can prime the fuel system with flip of switch without starting the motor.

----SEE WHAT I MEAN!---- Hahaha....

 

[Screaming Metal]

Simply click on the shaded portion at the end of the quoted part from Bob S. and you'll see your post. That was why I was able to answer like I did.

Jim

P.S. here is what you said in post 14:

Mechanical pumps are more reliable than electric IMHO. And you can get them anywhere, just in case it fails. Custom parts are [to me] for garage keepers/drag racer's and usually don't see any real road time. Do you remember the early MBR shows where the cars didn't even have to run? They pushed them out of the trailers and into the buildings. Not my thing at all. If it is worthy of MBR or any award, it should prove to be road worthy by doing a road trip of 50+ miles without failure. Off subject, sorry---SM's advice about fuel line size is great, but IMHO 3/8 fuel line will supply enough fuel to any engine up to 1000 HP with a blower as long as the carb/carbs can act as they should. Hard line is best for durability and safety with flex/rubber/braided or whatever between pump/filters/etc SAFE is far more acceptable than looks or performance IMHO/ which sometimes [opinion] aint worth saying at all .

bob

Yes , 3/8's is good for 1000+ blown horses on the street. I have a bad habit of saying things as it pertains to what I'm doing, Racing down the 1/4 mile. Sometimes, 1/8 mile. We're going way past twice as fast as we were back in the 70's, and a 3/8s line trying to feed a pr. of Dominators sitting on top of 900+ cu.in. motor, and when we plant the rubber to the track, even with our big pumps, special designed pickups, sometimes the computer says we're starved for pressure and the only way to feed it is to increase pressure and fuel line size, since we're pumping from the rear of the car.
The FC's have more twice the power than the 70's cars had, not to mention the Altereds with which I mainly work with. And the tank is up front, pump driven off the front of the motor, sometimes we're close to leaning out.
Street cars can run 3/8s with no problem, even the prostreet folks.
Its safe to say that 80% of the perf. street cars can get by with 5/16's line.
If your planting the tires hard enough to need 3/8s fuel line, you need to get off the street before you hurt someone....thats what tracks are made for