Can one bubble flare stainless steel line?

[In The Ten Ring]

I have a pre-bent piece of stainless tubing fuel line for my truck's pump to carb section (inline tube.com).

I was wondering if I could cut that in two, remove a section, bubble flare those ends and insert a fuel filter before the carb.

Will a standard (oem metal) flare kit perform that function or do I need a different flaring kit?

[Lou Boffa]

subbed

[RKS0069]

It will work but it might take a few tries to get it right. As far as I know the bubble flares are a European thing. These trucks used inverted 45 degree flares for the fuel and brake lines.

[67 chevelle]

stainless gets single flared and uses special flare tools and fittings , its also a pain to do

[Fitz]

Originally Posted by In The Ten Ring

I have a pre-bent piece of stainless tubing fuel line for my truck's pump to carb section (inline tube.com).

I was wondering if I could cut that in two, remove a section, bubble flare those ends and insert a fuel filter before the carb.

Will a standard (oem metal) flare kit perform that function or do I need a different flaring kit?

Different flare kit won't help. Stainless will crack and that is not a good place for even a small air leak..

[mike16]

it may or may not crack depending on the alloy and heat treatment.

But its stainless steel and it work harden's

very hard on tools.

maybe call a vendor like inline tube. they may be able to do it.

[In The Ten Ring]

Originally Posted by RKS0069

It will work but it might take a few tries to get it right. As far as I know the bubble flares are a European thing. These trucks used inverted 45 degree flares for the fuel and brake lines.

Maybe so. My original supply lines have something that looks like a bubble flare but not exactly. I may have to make my own under hood line from left over poly armor tubing I used to make the rest of the supply line.

[57taskforce]

If you made the supply line from poly armor, why not cut and flare that for a filter? In all honesty i prefer the filter before the pump anyway because then the pump is protected from dirt as well.

[Davidf]

What I do (never have done this on SS tubing): I use my double flaring tool and stop after the first step. This bulges the end of the line so the hose/clamp cannot slip off.

Also, I am in the camp that says single hard line between pump and carb. Filter goes ahead of pump. This reduces probability of ruptured fuel line, under pressure, causing a fire.

[MARKDTN]

Originally Posted by Davidf

What I do (never have done this on SS tubing): I use my double flaring tool and stop after the first step. This bulges the end of the line so the hose/clamp cannot slip off.

Also, I am in the camp that says single hard line between pump and carb. Filter goes ahead of pump. This reduces probability of ruptured fuel line, under pressure, causing a fire.

Neither of you have had pump troubles as a result of making the pump draw through a filter? I tried that on my '83 and it ate the pump in a few months. Most pumps are not designed to have a pressure drop before them. No OEM that I am aware of has a filter before a pump, whether mechanical or electric.

[leftybass209]

Originally Posted by MARKDTN

Neither of you have had pump troubles as a result of making the pump draw through a filter? I tried that on my '83 and it ate the pump in a few months. Most pumps are not designed to have a pressure drop before them. No OEM that I am aware of has a filter before a pump, whether mechanical or electric.

I feel the same way. A filter before a mechanical pump is not correct. If there's a need for a filter before the pump, then the root cause needs to be addressed ie: clean the tank and install a new pickup screen.

A simple test for this is, suck or blow air through a straw. Then pinch it off a bit and try and maintain the same pressure. If you get tired faster, and you will, so does your fuel pump.

[Big Kev-O]

My electric Holley Mighty Mite fuel pump included a 100 micron filter to be installed before the pump. If I recall the instructions said to not to use anything under 100 microns before the pump so flow is not restricted. After the pump I use a 10 micron. I cleaned the tank when the pump was installed 9 months ago. No issues yet. A screen filter cleans particals up to about 100 microns in size and doesnt restrict flow until it starts to clog. When your screen filter cloggs it's time to check the tank.

Getting a little off the subject. I have used my double flare tool to make some pretty good bubble flares but I wouldn't try it on a pre bent stainless. Why a bubble flare? What type of filter are you using?

[Davidf]

I have not. I do it this way because that is the way most marine engines are done (and I have a boat(s) with marinized SBC or Ford engines). Fuel filter is always head of mechanical pump with hard line from pump to carb. You don't want leaks in a boat. Only problem I ever had with a boat is when I used a hose clamp that was too large. The uneven clamping force allowed an air leak on the suction side of the fuel pump...that definitely caused fuel starvation problems. Took me awhile to find that one. Also, keep in mind that boat engines run hard and at the top end of the rpm/hp range.

For my truck, I don't run it hard ever...

When I had my 1971 Camaro (family was original owner) the only fuel filter was in the carb inlet. Hard line from pump to carb. The bronze filter was sufficient.

[BossHogg69]

I run an 85 micron filter right after the tank, aluminum 1/2" fuel line along the frame rail with nylon braided -8AN line coming from the hard line to the fuel pump, then another -8 line coming off the pump to a 40 micron filter right at the carb. All 37* single flare connections. Holley 12-454-25 mechanical pump. No leaks, not even on the first tank of fuel (thank goodness). The AL fuel line is very easy to work with and flare. I've heard SS was a bear to work with, but I've never flared/built lines with it myself.

[In The Ten Ring]

This thread deviated a bit.

[Ruscal]

We use SS fuel lines on race cars at our shop. The stainless steel makes nice clean lines and has not presented any problems with cracking for us. We use 37 degree AN (single flares) done with a simple clamp, wishbone tool. We have never tried double flares on stainless, as it can crack when worked like that. We have used stage one of a double flare tool to bulge the tubing to form barb fitting like bulge. We place the hose clamp close to the bulge, with good results. On fuel injection vehicles we don't use hose with clamps, just AN fittings on everything. I chose to locate the fuel filter between pump and carb on my C10 so the pump does not have to suck through the filter. Pumps can push much better than pull. If you choose to use a filter before the pump it would make sense to make it a coarser screen type sized just fine enough to allow particles small enough to not harm the pump through the line. Larger filters are better than small one due to having more screen area which buys you more time between filter maintenance. A finer secondary filter after the pump could have finer element protecting the tiny carb/jet passages.
Above are only opinions. Do your research.
Russ