MIG wide gap?

[MrBlobby]

Hi.
my first real job is to weld this fuel flap into the main body of the tank, to obtain a smooth tank top. Trouble is, its a wide gap and I'm wondering how to close it up - maybe introdule a filler strip?

What do you guys think?

Regards
Steve

 

[MrBlobby]

Oops,
forgot the pic

 

[will123thomas]

in my experience ive found the tommy two weave beaver weave special works lol you shouldnt need to put a filler in it unless the strength of the weld is important, if it is then putting some round/square bar in the gap should do the trick

 

[pedrobedro]

Personally I'd take that out and make a plate to fit the hole out of some 20g sheet then grind the weld down flush or just use body filler round it as it is to hide it

 

[will123thomas]

Personally I'd take that out and make a plate to fit the hole out of some 20g sheet then grind the weld down flush or just use body filler round it as it is to hide it

that seems a much better idea that mine lol

 

[MrBlobby]

Thanks Chaps

yeah, I've thoguht about starting with a new piece of steel. Trouble is, being a petrol tank, it's a compond curve and I'm not sure I can bend the plate both ways.
Any advice on forming compond curve would be handy

Steve

 

[wyn]

Are you relocating the filler cap/pipe etc, and just welding up the old flap that covered it all ?

 

[Drains]

How wide is that gap Mr B?, and how thick the mat'l? A wee gap - 1-2 mm won't hurt at all if your welder settings are good for it.

 

[gordon stephenson]

Hi,
Can't you take off the flap and dress the outer lip flat, therefore making the flap large enought to fit the hole far better for welding, Just a thought!

 

[MrBlobby]

The aim is to create a smooth tank top with a central alloy 'Monza' fuel cap. So the blanking panel will have circular hole and monza connector collar brazed in.
Metal on the tank and flap is about 0.6mm I guess and the gap I have to weld is 5mm.

Gordon - that's not a bad idea. That way i keep the correct curves of the original flap. Either way it has to be a fuel-tight seam.

Steve

 

[pedrobedro]

By the time you've cut out for the new cap you will not have much of the original curved surface left and I doubt you would notice the flat under the cap lip anyway. With a bit of grinding and filler round it will be invisible. Slightly thicker than the cap will be easier to weld in and I don't understand why the seam has to be fuel tight, surely your Monza cap will be secured to the filler neck inside the bodywork ?

 

[wyn]

Either way it has to be a fuel-tight seam.

This sounds a bit like it's going to have the original fuel cap area behind the flap holding fuel.

I'm sure that area will just be spot welded to the outer skin and could have plenty of leaks.

The best bet would be to have the new cap and filler tube connected all the way to the tank with a new hose.

I could have been reading this all wrong.


If you are going to do it like that take the tank off.

 

[MrBlobby]

Yes there will be a new hose attached to the brass collar that the monza cap attaches to.

I was going to to cut out the existing filler neck and surrounding metal that lives below the flap and feed the new hose down into the tank.

The tank in question is a spare and hasn’t had fuel in for years…. Should be safe!!

 

[hotrodder]

Fuel flap has only a gentle compound curve in it? Easy(ish) way to get a gentle compound curve in a small panel is to just hit it with a hammer on a hard, flat surface. Draw a grid onto the blank, about 3/4" spacing, as a target for the hammer. Hit the panel once in the middle of each square, keep the force of the blows even and use a low crown hammer. After the first round of hammering the panel will have domed very slightly, if you need more do another round of hammering this time hitting where the grid lines intersect

Having been 'empty' for years is no guarentee that the tank will be safe/inert, fuel varnishes can be trapped in seams. Is the filler neck not seperate from the tank, joined via a rubber connecter?

 

[MrBlobby]

Thanks for that, I'll give it a try.
I have decided that a new panel is probably the best way to go, and with this hammering technique things should work out well.

Under the flap is the top of the tank which has a standard twist cap leading directly in to the tank - no tube.

The monza cap has a 2" rubber tube that I'll feed through.