Originally Posted by smiffy6four

Weld penetration isn't so much about the wire thickness, it's more about the power setting on the welder. 025" wire is best for auto body stuff, you can weld thinner stuff with it without burning through. Using 035 requires more heat to melt it in properly, so burn through is more likely to be an issue. If you feel you aren't getting enough pentration either inch back the wire feed slightly or up the power a bit. Tack the edges of the repair section in every 2 inches or so to start with, then add short welds in between each tack, and repeat until you have it seam-welded. Doing small bits at a time reduces heat build up and distortion and burn through. If you have to bridge a burn through area, drop the power one notch, up the wire feed so that it barely melts in and flick the trigger rapidly to give small quick bursts of wire. When you have the hole filled with what looks like bird droppings, correct your power/feed setting for normal welding and go over what you just did to smooth it out.

Oh, and practice on some scrap stuff, and experiment with turning the wire feed knob slowly while welding(NOT the power knob, you'll hurt the welder)and you will also get to recognize the sound of a good weld being laid down. I clean my areas to be welded with a bit of paint thinner to degrease it. Just make sure it's dry and the thinner is capped and well away before hitting the welder. Have a fire extinguisher at your elbow when welding. Enjoy! Welding is great fun when you get the hang of it.

Oh, and your car is worth doing, I have saved far worse machines from the crusher Here in Northern Ontario, rust is quite severe. Guys from down south wouldn't look twice at stuff we consider do-able up here.

I usually make a cereal box cardboard template before ever cutting any metal. It's so much easier to rough it in cardboard, then fine tune it with a pair of scissors. Then just trace your pattern onto metal and it will fit first time, no grinding req'd.