Fuel System Plumbing Question- Proper AN Hard Tube Adapter Use ?

[kitcarbp]

Ok, its time to connect my AN-6 size fuel hose to my chassis' plated STEEL hard fuel line (3/8).

I see that a few AN fitting companies offer the hard-tube adapters to help you connect the AN-6 female hose end to a hard ALUMINUM tube, this type of adapter uses a compression fitting for the hard tube side.

The Earl's catalog ( as an example has -6 to 3/8" hard tube) clearly states the max pressure for their hard tube adapters is 50 psi which is fine, since I will run less than 8 psi for a CARB set-up. My question is; it seems these fittings are designed for use on ALUMINUM hard tubes not STEEL hard tubes for fuel lines. Can I use this hard tube adapter for my STEEL hard tube or will I suffer leaks because the compression ferrule will not seal against the steel tube correctly? Before I waste 10 bucks on this fitting I would appreciate some experienced feedback here? A pair of stainless screw drive clamps are not elegant but would also do the job at such low pressures but looks well....... too "shade tree" for me. Advice ?

Thanks

[Jerry Clayton]

they will work on steel but why do you have such a small fuel line??

[Ronbo]

Should work, other option is to flare the tube and use a tube nut and sleeve. Be carefull as AN uses a 37deg. flair not 45 like most standard flair fittings.

You could also use a brass compression to pipe thread fitting and then screw in a AN to pipe adapter as well.

[kitcarbp]

Thanks for the feedback, my typo, it is a 3/8 steel fuel line, not 5/16 , I will give this adapter a try.

[diegokid]

The hose clamp will work and there aredress up ends and fuel line covering in your choice of colors. In short the ends look like an anodized nut that the clamp sits in. You just need to turn the nut so the adjustment part of the clamp isn't visible. You can find these coverings at most automotive stores in the dress up sections.

[Roscoe]

Rip out the hard line and use all braided hose...

Roscoe

[kitcarbp]

Ok, I have found the right product to cover this connection. Aeroquip makes a line of hard tube fittings for either flared or flareless options. The product is called "Versil Flare" and is for use on steel lines. This allows you to connect a AN-6 union to the -6 hose. Best price I found was on the net at Valley Hydraulic Service Inc.

[Nor Cal Al]

Parker or Swaglok make industrial compression fittings for this use. I used Swaglok on my car. Just Google for your local distributor. Typically a $25.00 min order.

[Bobcat]

I worked for Parker Mobile Hydraulics Group for 20+ years and the only "negative " thing I can say about Swagelok is that a lot of their stuff is designed for instrumentation applications and tends to carry a higher price tag than Parker . However , Parker also makes an instrumentation fitting .... however , in a high vibration area application , try to use an industrial grade compression fitting as it will work as well and shouldn`t cost as much as an instrumentation fitting . A problem I have seen in extreme vibration applications with bite type fittings is that where they bite can become a stress riser and possible failure point .... stay with compression type fittings. However , both fittings are first class .
I personally prefer flare fittings for oil and fuel .
Doesn`t mean there are any problems with the others , just my preference .

[kitcarbp]

Thanks Bobcat, Have my steel hard tube compression fitting installed now but, I went to my local Parker store and Parker did not have a -6 AN steel hose end for other brand (size) O.D. hoses, Parker fittings are designed for Parker -6AN teflon lined hose only with a smaller O.D., I am using AUTO (RUSSELL) type -6AN hose with 0.55" O.D.

I ended up spending 18 bucks buying a brass 3/8 barb fitting w/ pipe thread on other end then connected to a steel -6 AN swivel hose end, not elegant but reliable. As an engineer, I laughed on the way home telling myself I should just use a nice $0.99 wide quality hose clamp and spend the 18 bucks somewhere else. Still may take this stuff back. UPDATE- WILL NOT USE THE PARKER FITTINGS, FOUND MORE ELEGANT SOLUTION USING STEEL AEROAQUIP AND EARLS FITTINGS. SEE MY NEXT POST BELOW

With 8 psi max fuel pressure this is over kill anyway but if I upgrade to FI one day I wanted the fittings to be good for up to 60 psi.

[kitcarbp]

Here is one correct solution when connecting your hard steel line on your chassis to flexible steel braid -6 AN line on your engine.

Using a 3/8 inch Terne Coated steel line on your chassis, I used $ 2Aeroquip -6AN coated steel compression fitting with a coated steel $2 -6AN male union. Then found a $ 7.50 coated STEEL -6AN hose end from Earls AUTO-FIT product line. I could have also purchased the 37 degree flare tool but since I only had two flares to make on either end of the chassis, I decided to use a compression fitting instead. Gas line to hold no more than 8 psi for my system pressure so this will work. Make sure you use good quality gasoline/fuel grade steel flex hose that has a co-extruded inner vapor barrier otherwise you'll wonder why the garage smells like a pool of gas. There is a lot of aftermarket junk out there for steel braid hose, be careful and happy plumbing.

You dont want to mix aluminum and steel connections and expect a long term reliable joint.

[sllib]

I thought I was using a fuel quality braided hose on my fuel lines (Jegs) but evidently I am not as my garage smells like a pool of gas and I have no leaks and it's not coming from my carb vents. The sweet smell of gas doesn't bother me but the thought of what might happen if it was combined with a tiny spark is terrible to consider. Who makes a "odorless" braided hose? Thanks.
Bill Stradtner

[kitcarbp]

Bill, Aeroquip and XRP are two of the better ones, visit their websites to learn more. If you run pump gas you need to make sure you are using alcohol compatible hose since there is 10% alcohol in most pump gas these days. You wont find XRP and JEGS or SUMMIT. I used Bruces on-line speed Shop out of New Jersey (check the web brucesspeed.com) for reasonably priced XRP fittings and hoses and great service. I feel better supporting local speed shops as well, no matter where they are located.
I was encouraged to use XRP when I learned NHRA Top-Fuel teams (amongst other pro series racing) also use XRP for Nitro-meth fuel and oil lines. Bottom line is there is more to steel braid hoses than meets the eye. You get what you pay for with steel braid hose. Remember, aftermarket specs are almost non-existent. The private label or no name steel braid is junk, throw it out, I have a piece of it and use it for my coolant overflow bottle vent only where it cant do much harm, I hope! Honestly, be safe and good luck.

Bill

[sllib]

Bill;
Thanks for the info. Here I go again, another rip out. At least I can do this while the body's going for paint.
Bill Stradtner