OK question about welding 1/8" alum pan

Whats the best technique to keep it from not warping. Im gonna bolt it to the block when im welding it should i do it in 1" sections and flip from one side to side.

Im welding a pan flange one to a moroso pan

 

Bump

 

preheat it on a hot plate. bolting it to the block will definitely help.

 

I just did one. Preheat it with a small torch from home depot.
It only takes a few minutes. Do this after it is bolted down, then weld.
Just make sure to move around as much as possible and backstep.
While cleaning it I discovered a very quick way to preheat.
I was preheating and I hit a little puddle of brake cleaner...
The I remebered highschool hairspay antics, VOILA!
Done carefully, it takes only seconds to get a good heat spread.
Please don't burn anything down.

 

OK cool. Talked to a budy mine said to acetone it to death get as much of the old oil out of the old flange then tac it. then heat it with a propane torche and do small sections.

Ok ill post some pics up tomorrow

thanks.

Another note i usualy run my argon at 15psi feel sometimes i get better welds out???