anyone sump a stock gas tank
 

has anyone welded one of the sumps that you can get on a stockgas tank. if so how was it.

A local radiator shop does that...

I have . Piece of cake. Don't just cut a big hole in it use a big hole saw instead, and cut several holes all bunched around each other...it will act like a slosh baffle. Just wash it out two or three times with super hot soapy water and weld it up. No big deal. If you are nervouse about welding on the tank you can back purge it with argon while you weld to prevent a kaboom ( I didn't..just washed out good) I have heard that running a car exhaust into it would be an option too...but can't varify that.

gas tank
 

yea, i would just fill it up with water a few times, then just clean off the galvinized like coating real good and weld it up! And yes if you want to be super safe, run a line with argon and fill the tank and let it run threw the tank as you weld!
Making it a super tight fit and being clean steelit will be cake!

You can also put some dry ice into the tank also before welding.

I had mine cleaned out at a radiator shop as was suggested above and then welded it up. Worked out fine.