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Fuel rail....TIG, solder, or braze

Doyle4281

Plastic
Joined
Aug 15, 2012
Location
United States
Hello all, I need some advise on some modifications I need to do on a factory Nissan fuel rail. I need to attach a -8 make jic fitting to one end, as well as attach an 1/8 npt female boss to the end of a tube. Being that there are existing brazed joints very close to the area being modified, what method should I use. I don’t want to damage the existing brazed joints. I know a talented TIG welder, however we haven’t tried this type of modification before. I thought about sending it to someone to be silver soldered or brazed, but I am unfamiliar with process and it’s strength capability. The rail is for a fuel injectors turbocharged vehicle, so will see upwards of 80 psi fuel pressure. I would post pictures if I knew how. Thanks
 
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Why dick around with the stock rail?
It probably won't have the volume to keep up with the injectors.

Just get a blank rail and build what u want fitting wise.

Is this for a 240?
 
The rail is for an RB26 Nissan GTR engine. The reason for the modifications is that it needs to maintain an OEM appearance, however needs to reliability of the AN fittings
 
Reliability? Proper rubber hose and barbed fittings are plenty reliable. That said a lot of those fuel rails are plated steel, some are SS. You can tig either with the proper fitting and prep. Tig would be my go to personally, but silver solder would work fine.
 
Reliability? Proper rubber hose and barbed fittings are plenty reliable. That said a lot of those fuel rails are plated steel, some are SS. You can tig either with the proper fitting and prep. Tig would be my go to personally, but silver solder would work fine.

The factory rubber feed is too smal and the rest of the fuel lines are -8 AN. The interior volume of the rail is just as large as any aftermarket rail.
 
At 80psi, rubber hose and a hose clip would do,,,

I’m sure it would, but the fitting is too small. Its an 800hp engine and the 5/16 fuel line is not enough. The information I’m interested in concerns the process of attaching the fitting in very close proximity to a brazed joint. I’ve seen a lot of suggestions of brazing or silver soldering. For me TIG welding would be the best option as I know a lot of welders. However, I fear that the heat from the weld will weaken the brazed fitting near it. I’d like to post pictures, but the phone won’t allow it
 
I would think if everything was clean even if the tig got the silver solder flowing it would just flow in place at the joint. Maybe a little flux on the original joint just in case. A good tig hand is not going to spend much time there. Just thinking out loud as I have
not tried this.
 
I would think if everything was clean even if the tig got the silver solder flowing it would just flow in place at the joint. Maybe a little flux on the original joint just in case. A good tig hand is not going to spend much time there. Just thinking out loud as I have
not tried this.

I’m thinking the same. The surface will be prepared very nice and I will machine tgevAN fitting so it mates up
In a pocket rather than a butt weld
 
Shouldn't be any problem for half-decent welder to weld the fittings 1/4" away from the silver brazed joints. I doubt you need to get them closer than that.
 
Shouldn't be any problem for half-decent welder to weld the fittings 1/4" away from the silver brazed joints. I doubt you need to get them closer than that.

I always silver solder fuel rails, no risk of burn through and sugar inside the tube as with TIG. Beautiful radius between the fitting and the tube. done properly the tube would split from over pressure and the silver solder joint will not fail.
 
I always silver solder fuel rails, no risk of burn through and sugar inside the tube as with TIG. Beautiful radius between the fitting and the tube. done properly the tube would split from over pressure and the silver solder joint will not fail.

Me the few i have done i just treat as any other TIG pressure tubing job and use a back purge, do agree though, you need to do something to ensure internal cleanliness post jointing, Flux residues would be a bad thing to get in the injectors!
 
I always silver solder fuel rails, no risk of burn through and sugar inside the tube as with TIG. Beautiful radius between the fitting and the tube. done properly the tube would split from over pressure and the silver solder joint will not fail.

Low temp silver solder or higher temp brazing? I'm assuming brazing?

Stainless is bit tricky to wet with low temp silver solder in my expericence.
 
This is the fuel rail I need to modify. the cylindrical end is .550 OD. I will be drilling through the center, and attaching the -8 AN fitting to the end. The tube that comes off the cylindrical end is one of the things that concerns me, as applying heat that close to a brazed joint, im concerned may cause an issue. Ill be glass beading the whole thing, and getting is plated after.


IMG_1410.jpg
IMG_1411.jpg
 
good gawd! that looks awful!

what material is that? looks like a "silver soldered" assembly.

(that term can be confusing, as both lo temp "soft solders" and silver containing "braze alloys" are both described as such, and to make it more confusing, many braze alloys don't contain any silver at all, but the simple difference can roughly be described as "soft solders" are usually primarily tin and/or antimony a/o lead a/o bismuth and sometimes silver in small amounts, and "braze" alloys start melting much higher, after things start glowing red.)

it wouldn't ever have been a "soft solder", of corse, for that application.

I would absolutely stay with the method it was originally fabricated with, and to reduce the chance of completely re-melting the other joint, I would use a low-ish braze alloy such as "easy-flow 45". to ensure adequate joint strength, its just a matter of having an adequate design and "wetted area", preferably putting the joint in shear. for a pressure as low as 80 PSI, it will be no problem at all.

also, with a close proximity to the braze joint, you run the risk of boiling the zinc in the other joint if you TIG it, and that really makes a mess of things!:eek:
 
good gawd! that looks awful!

what material is that? looks like a "silver soldered" assembly.

(that term can be confusing, as both lo temp "soft solders" and silver containing "braze alloys" are both described as such, and to make it more confusing, many braze alloys don't contain any silver at all, but the simple difference can roughly be described as "soft solders" are usually primarily tin and/or antimony a/o lead a/o bismuth and sometimes silver in small amounts, and "braze" alloys start melting much higher, after things start glowing red.)

it wouldn't ever have been a "soft solder", of corse, for that application.

I would absolutely stay with the method it was originally fabricated with, and to reduce the chance of completely re-melting the other joint, I would use a low-ish braze alloy such as "easy-flow 45". to ensure adequate joint strength, its just a matter of having an adequate design and "wetted area", preferably putting the joint in shear. for a pressure as low as 80 PSI, it will be no problem at all.

also, with a close proximity to the braze joint, you run the risk of boiling the zinc in the other joint if you TIG it, and that really makes a mess of things!:eek:

Thanks for the info. I have no experience with silver soldering, however I have been doing some research. If I were to look for someone to do this work for me, who/where would I look? Welders, radiator repair shop, esc. I think it would cost me more to buy the materials to do it myself than to pay to get it done. I’ll of course do all the prep work
 








 
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