Weld or solder? Fuel tank

Need to cut out old fuel tank sender mount ( Alfa Romeo) and install a Ford mount,so I can install the Ford fuel pump system. Weld or solder?

I would say:  Braze.

I plan to cut a round or square section out of the Ford tank and mate it to the Alfa Romeo tank

Spot weld, then solder.  Welding will be very tough to seal, unless you are very good, and solder might not be strong enough for a large area like that.

Holley(I think) also makes a bolt on flange with a thick seal to absorb the thickness of the ribbed panels, but it might not be super budget friendly.

I second Dr. Hess.   While soldering might work, I would be worried about the solder joint cracking over time from vibration.  Will the Ford fuel module fit through the Alfa tank opening?  If so, make a new top plate for the fuel module.  And late idea, why a Ford fuel module?  Might something aftermarket work easier.   not fuel pump, but HydraMat as a fuel pick up on Alfa sending unit.  And add electric fuel pump to stock unit.

I like the idea of spot weld and solder.i can do that☺

Noddaz, the Alfa one barely fits. The Ford one is way bigger. And why the Ford fuel pump and sender? Photo.

I am redesign my dash. Useing Ford mustang v8 cluster. Mush cheaper than buying all those gauges each

Skinnyg. No it's not

Sorry, I meant it in humour - a line from "Get Smart."

Sparks and flame are usually a cautionary tool around gas tanks; I am cautiously aware of the potential for "ka-frickin-boom." Which reminded me of the movie. Be careful, but by all means: 

In reply to SkinnyG :

Not worried. You should see the flames I get from the Alfa Romeo bb ..every time I go there,I must wear my nomax undies.

Alsi.tank has been dry for 3 years,if I do weld/ solder,I will fill the tank full of dry ice.

noddaz said:

I second Dr. Hess.   While soldering might work, I would be worried about the solder joint cracking over time from vibration.  Will the Ford fuel module fit through the Alfa tank opening?  If so, make a new top plate for the fuel module.  And late idea, why a Ford fuel module?  Might something aftermarket work easier.   not fuel pump, but HydraMat as a fuel pick up on Alfa sending unit.  And add electric fuel pump to stock unit.

 

 

I wouldn't be too worried about solder cracking if it's done right.  It's not stressed in any meaningful way.  Plus, I had to source a fuel tank for an old kit car and it turned out the tank was a stock Chevette tank with the fuel filler cut out and reinstalled somewhere else, with solder on the filler neck and on the blockoff plate.

Nothing against adding a few welds for belt and suspenders.  There's no kill like overkill.

If the modificaton is solely being done to use Ford gauges... I'm fairly sure that Fords have used the same resistance since time immemorial. Might be easier to bung an older Ford sender on the Alfa part.

Understood, Ford gauge cluster, Ford fuel module.  At least those two will talk to each other nice.

Welding, soldering, brazing on used fuel tank that has been empty. (And you are working on two of them.) When heated will fumes leach out of the metal?  I don't know.  But what a guy I know did at his home shop when he had to weld on a used fuel tank was to 1, do it outside.  2, run an exhaust hose from a running vehicle into the tank to keep the tank flushed with inert gasses.  He didn't blow up.  Just a thought.

How the bike shop welded a Triumph tank for me:  Drain/flush/clean/flush. Fill with water.  Let sit.  Light match over mouth. Weld.

This is a simple circuit. I would leave the Alfa sender and use a few resisters to provide accuracy. If that's not acceptable I would solder the two pieces together. Sheet metal this thin is difficult to weld or braze. 

In reply to Dr. Hess :Funny, thank you

I wasn't joking, guy.  You light the match over the mouth when it's filled to the top with water to burn off any residual gas that leached out of the metal.  That's how they did it.  It was a very old school shop.

Would not dry ice  work better? Let it full the tank full of cold co2, displace  all  o2.? Agian tank empty for 3 years

I really don't want to see the afterlife anytime soon

Even better  some water in bottom of tank, 1 or  2 gallons, then drop in dry ice

Will fill with co2 faster

I've soldered up leaks in gas tanks still holding gas before I knew any better.  Does the tank smell of gasoline? If not proceed with what ever.

Dr. Hess said:

I wasn't joking, guy.  You light the match over the mouth when it's filled to the top with water to burn off any residual gas that leached out of the metal.  That's how they did it.  It was a very old school shop.

I had to braze a fitting into a used fuel tank.  I drained it, filled it with hot water to force any residual gasoline to evaporate faster, drained it again, and threw a lit match in it.  No poof.  The brazing went uneventfully.

Poof!!! Get next fuel tank to work on.

I've welded gas tanks. Clean & dry then have someone hold air gun from compressor gently blowing air through tank while welding as an added precaution.

I would just weld it too. I MIGed my Challenge car tank from scratch, from a sheet of 20ga steel. Pulse technique just like when doing sheet metal. It never leaked.