Anyone running fuel line in factory boxed GM A-body frame?

[ed1le]

I'm about to install braided fuel line in my '70 Skylark convertible w/ a factory boxed frame and was wondering how hard it is to run the line inside the frame (body is on the frame so I'll be working from the bottom) or if there is any internal bracing/blocking that might prohibit it. Thanks!

[MonzaRacer]

Do not run braided front to back, buy a good flaring tool, build 3/8 or 1/2 in in suitable lengths or have a good cutter.
Use double flares with inverted flare unions, OR the steel compression fittings available from NAPA.
Braided line doesnt seem to hold up well over long term and if you build a good solid line you can also buy vinyl coated claps that can be attached to the frame with the 3/8 self tapping body bolts.
I have actually made the straps with sheet metal and the vinyl tool dip also.
I have a hydraulic flaring tool and can make 1/2in flares and even have the 37 deg flares to hook to AN connectors too.
And yes several places the frame goes boxed so you have curves and such.

[MonzaRacer]

OK another recommendation would be to look into the plastic fexible line used on the newer cars its actually very durable, much more suitable to make a fuel line and has been used for probably the last 10 to 15 years and I have only seen man made damage never degradation. and dorman makes a kit to attache different types of hook ups and you can add in newer type fuel filters with quick connects and such.
They are also rated for higher pressures like fuel injection uses in the 60 to 80- PSI.

[LowBuckX]

I run teflon braided front to back ... Should last a long time .....rubber hose with the braided stainless seeps and causes gas odors. But the teflon was 3 times the price..

[CarlC]

Teflon yes, rubber no.

[TonyHuntimer]

Teflon yes, rubber no.
X2!

This is a common tech question that I get for Tony's Garage.

Don't run rubber front to rear. It's a waste of money and as LowBuckX pointed out, the rubber hose breaks down, weeps and causes gremlin fuel odors. Hardline is the best and cheapest way to go. I've seen a magazine with an article telling its readers to use steel braided rubber hose from front to rear. It showed how little the magazine knew about tech. I had a good laugh. Unfortunately about 40,000 readers of the magazine probably didn't know better. :slap: I've made mistakes too, so I'm guilty too. Fortunately for me, Camaro Performers allows me to make amendments in Tony's Garage. :)

Teflon is a good alternative, but very spendy because you have to buy the expensive hose and then add on the proper fittings.

[Randy67]

I don't think you will be able to get the line through the boxed sections. Not to mention it would be free to move around in the boxed section since you wouldn't be able to clamp it in there, which could cause leaks.
I would run metal line like the factory did, but cut it into 2 pieces so you can put it on with the body still on. Fine Lines, Inline Tube and others like them can make the factory style line layout in larger sizes like 1/2" if you need more fuel.

[wmhjr]

I tried getting -6AN stainless hard line through the boxed sections. In a '66 A-body starting from the rear the hard line starts near the center of the rear crossmember, goes sideways and down to the frame, runs along the frame to where it narrows just behind the front wheels/front crossmember, where it goes through a hole in the frame and curves through. There are gussets inside near the front crossmember. I was able to get a -4AN vent line through there - barely - but there was no way the -6AN hard line was going through there, especially with the fitting on it.

[67 455 Bird ragtop]

I tried getting -6AN stainless hard line through the boxed sections. In a '66 A-body starting from the rear the hard line starts near the center of the rear crossmember, goes sideways and down to the frame, runs along the frame to where it narrows just behind the front wheels/front crossmember, where it goes through a hole in the frame and curves through. There are gussets inside near the front crossmember. I was able to get a -4AN vent line through there - barely - but there was no way the -6AN hard line was going through there, especially with the fitting on it.


Not to mention a return line. So a side question to this thread would be run line on the inside or outside of the frame or does it really matter ??

[Randy67]

Not to mention a return line. So a side question to this thread would be run line on the inside or outside of the frame or does it really matter ??

The A-bodies have it on the inside of the frame, probably to shield it from side collisions. F-bodies up to 81 had it on the outside of the subframe, but their framerail is farther in compared to the A-body.

[wmhjr]

On a boxed A-body frame, IMHO they should be 2/3 down the inside boxed frame. When you drop the body back on the frame, that will result in the lines being in about a perfect location as far as clearance from the frame/body, while staying protected.

[PhillipM]

I know a lot of people run braided all the eay from the back. I just prefer to hard line it. I think it looks much more O.E.

[ed1le]

I also know of people running it front to rear without issue, at least not that I know of. I did do some online research though and found some threads w/ people complaining of fuel smells from rubber lines and read that it's due to the ethanol content in today's gas which “attacks” the rubber hose. Not sure how true that is. Maybe over long periods of time? However, if it’s that harsh on rubber, wouldn’t we also then have leaking o-rings, etc. in our carbs, fuel pumps, etc? Also, even if I run hard line, I'll still need to run hose from the line to the pump and from the tank to the hard line. I do have a coil of ½” OD aluminum fuel line from another project (and a double flare tool) but just spent a lot of dough on this braided line.

[wmhjr]

IIRC there is one thing to consider. I believe IHRA and NHRA require that if you use braided line you must leave it exposed so that it can be inspected. IOW, you can't legally run braided "through" the frame. You can with hard line.

One other thing. You mention rubber. O-rings, seals, etc are made from all kinds of compounds. Typically it is not just plain rubber, and even different brands/types of fuel lines are made of different compounds.

[Nicks67GTO]

http://inlinetube.com/

They have pre bent lines, main and return, for your convertible. They come OEM or stainless.

[wmhjr]

http://inlinetube.com/

They have pre bent lines, main and return, for your convertible. They come OEM or stainless.

Those are the hard lines I used, in stainless. -6AN supply, -4AN vent. Like I said, I was able to get the vent line through the frame after a LOT of effort. No way the -6AN was going through the front in the stock location. I had to cut the supply line, add a fitting, and then use a section of braided for that section.

[ed1le]

"One other thing. You mention rubber. O-rings, seals, etc are made from all kinds of compounds. Typically it is not just plain rubber, and even different brands/types of fuel lines are made of different compounds."

This is understood. My point was that if there are issues w/ the braided lines that are designed for fuel, you would think there may be issues with other rubber based components.
Regardless, was just looking at the inlinetube site and see they make replacement lines in 3/8 & 1/2" in stainless for $130, not a bad price. However, my tank has a sump so I'd have to run line or hose to the sump. I think cutting the line and installing in 2 pieces would be the only way to do it with the body on the car & feeding it through that front of the frame.

[wmhjr]

"One other thing. You mention rubber. O-rings, seals, etc are made from all kinds of compounds. Typically it is not just plain rubber, and even different brands/types of fuel lines are made of different compounds."

This is understood. My point was that if there are issues w/ the braided lines that are designed for fuel, you would think there may be issues with other rubber based components.
Regardless, was just looking at the inlinetube site and see they make replacement lines in 3/8 & 1/2" in stainless for $130, not a bad price. However, my tank has a sump so I'd have to run line or hose to the sump. I think cutting the line and installing in 2 pieces would be the only way to do it with the body on the car & feeding it through that front of the frame.

The problem with the fuel lines IMHO is that they're not all created equal. I've gotten braided line from Fragola that is twice the quality of braided "fuel" line from Summit, for example. It's way heavier, and the guts seem to be of a different material. Who knows?

I think you're right about splitting the lines. I'm quite happy with the stainless fuel lines I got from Inline Tube. But, that 1/2" stuff is HARD to work with. You'll have a rough time with the body on the frame, and there is very little chance you'll be able to thread even the vent line through the front. What you may want to do is measure how far back you want the joint, and have them put -AN fittings there. In particular if you're running a rear electric fuel pump. I have less line pressure concerns with the RobbMC pump I'm running up front.