Fuel lines: Aluminum vs Steel vs Stainless

[theblindchicken]

I'm planning on hand bending new fuel line for my truck.

Specs: Mechanical Fuel Pump to a Quadrajet on a 350 SBC with full accessories on a street driven truck.

The issue: what material to go with? Measured out the old line at 5/16" tubing (measuring ID with Mitutoyo calipers came out to 0.317").

Aluminum will be easier to bend since its softer, but more susceptible to cracking.

Steel will be harder to bend, stronger, susceptible to rusting.

Stainless will be harder, more expensive, but not susceptible to rusting.

Planning also on wrapping it to help prevent vapor lock (going to be running headers).

Also, would a check valve be a good idea to help out with starting quicker?

Thanks.

 

[CSFJ]

Are those Ni-Cop lines rated for fuel also, or only brakes?

 

[Honky Kong jr]

Are those Ni-Cop lines rated for fuel also, or only brakes?

Yes. Easy to bend,easy to flare and won’t rust, but is soft so you wanna keep it out of harms way.

 

[78C10BigTen]

I'm planning on hand bending new fuel line for my truck.

Specs: Mechanical Fuel Pump to a Quadrajet on a 350 SBC with full accessories on a street driven truck.

The issue: what material to go with? Measured out the old line at 5/16" tubing (measuring ID with Mitutoyo calipers came out to 0.317").

Aluminum will be easier to bend since its softer, but more susceptible to cracking.

Steel will be harder to bend, stronger, susceptible to rusting.

Stainless will be harder, more expensive, but not susceptible to rusting.

Planning also on wrapping it to help prevent vapor lock (going to be running headers).

Also, would a check valve be a good idea to help out with starting quicker?

Thanks.

I am curious to see the responses to the check valve question. Ive often looked at an empty fuel filter and thought it would be hard to start. Also correct me if im wrong doesnt the mechanical fuel pump have something to prevent fuel from running back after shut off?

 

[Honky Kong jr]

The fuel in the bowl is generally enough to get fuel flowing

 

[78C10BigTen]

The fuel in the bowl is generally enough to get fuel flowing

All ya need is a squirt in the hole to get er started then the pump starts pushin. Correct?

 

[Rusty Nail]

Voted no check valve.

 

[Honky Kong jr]

All ya need is a squirt in the hole to get er started then the pump starts pushin. Correct?

Once it’s running that’s how it’s supposed to work.

 

[RustyPile]

Since the fuel level in the carburetor reservoir is below the needle/seat, there's no way for fuel to siphon out.. NO WAY.. If fuel is disappearing from the reservoir, the carburetor has problems that installing a check valve will not correct..

Aluminum is not a good choice for engine mounted fuel line.. I highly recommend soft stainless line designed for brakes and fuel lines.. Use a tubing bender and you'll avoid collapsing the line.. A double flaring tool is necessary also.. DO NOT run a rubber fuel line between the carburetor and fuel pump.. The Q-Jet has a built-in fuel filter.. If you feel the need to run a second filter, install a steel filter (not plastic) in line before the fuel pump...

If the fuel line is routed properly from the fuel pump up the front of the engine, across the intake manifold, heat from the headers will not be an issue.. I haven't treated a vehicle for vapor lock in probably 50 years.. Symptoms masquerading as vapor lock - yes - but not true vapor lock.. The third fitting on a carbureted engine [edit] fuel pump is a metered fuel return.. 99.999% of the time, this is all that's needed to prevent "vapor lock"..

Don't worry about bubbles in the fuel line or fuel filter, That simply means the fuel line is [edit] not 100% filled with fuel.. Nothing to worry about..

 

[RustyPile]

All ya need is a squirt in the hole to get er started then the pump starts pushin. Correct?

Yes, it's just that simple.. Unlike fuel injection that requires pressure to deliver the fuel, a carburetor needs only a vacuum source.. A couple "pumps" of the gas pedal, crank the engine and the carburetor take over...

 

[theblindchicken]

Thanks for all the help guys.

Was definitely planning on using a tubing bender for it, was just mainly unsure of what material would be best.

Prior to the current engine rebuild, the truck had a hard time starting once hot. Even though the fuel line had been wrapped previously by my father a long while back. So first assumption was the fuel was evaporating out of the carburetor and fuel line. I had issues with the manifolds cracking and/or not sealing well with gaskets. The increased engine bay temps definitely didnt help with fuel evaporation.

So looks like its a good idea to skip the check valve. Already had a fuel filter mounted along the frame underneath the cab.

 

[RustyPile]

Thanks for all the help guys.
.......<snip>........Prior to the current engine rebuild, the truck had a hard time starting once hot. Even though the fuel line had been wrapped previously by my father a long while back. So first assumption was the fuel was evaporating out of the carburetor and fuel line. I had issues with the manifolds cracking and/or not sealing well with gaskets. The increased engine bay temps definitely didnt help with fuel evaporation...............

Giving the vapor pressure of today's gasoline, fuel evaporation and/or vapor lock was probably not the problem. Witness fuel line wrap not solving the problem. If the engine was way down on compression, hot start would be a problem.. If the carburetor reservoir was empty, after sitting awhile, and the carburetor was a Q-Jet, my money is on leaking metering well plugs.. A very common occurrence on Q-Jets..

 

[theblindchicken]

Giving the vapor pressure of today's gasoline, fuel evaporation and/or vapor lock was probably not the problem. Witness fuel line wrap not solving the problem. If the engine was way down on compression, hot start would be a problem.. If the carburetor reservoir was empty, after sitting awhile, and the carburetor was a Q-Jet, my money is on leaking metering well plugs.. A very common occurrence on Q-Jets..

The hot starting issue would be that if I ran errands around town, and truck got all warmed up... if I would stop and go start her up again, it was though the starter didnt have enough torque to spin the engine well. This was with a stock starter and a high torque replacement. Different batteries as well.

It was like you were bumping the engine over, then on the 5th or so bump it would fire up with your foot to the floor.

Cold starts were no issue. Two pumps, crank it and fires quickly.

 

[Rusty Nail]

I also vote for stainless steel? That would be saa-weet!

After reading your last two replies @TBC my thoughts went directly to the battery cables.

Sounds like some of the issue is carburetor related WITHOUT KNOWING OFF HAND the specifics of your truck except it's round eye win!

 

[RustyPile]

The hot starting issue would be that if I ran errands around town, and truck got all warmed up... if I would stop and go start her up again, it was though the starter didnt have enough torque to spin the engine well. This was with a stock starter and a high torque replacement. Different batteries as well.

It was like you were bumping the engine over, then on the 5th or so bump it would fire up with your foot to the floor.

Cold starts were no issue. Two pumps, crank it and fires quickly.

Bad battery cables, loose cable and/or corroded connections, starter not having a good electrical connection to the block, battery not up to the task - all are contributing factors.. Those clamp-on replacement battery cable terminals are the worse for causing that problem.. A normal good working starter draws 180 - 200 amps, with the initial current surge being above that.. A hot starter and hot engine really "pulls" hard on a battery..