Had a friend with a cast aluminum valve cover who had accidentally ground a hole in it when trying to add some clearance. He had patched the hole with epoxy but now wanted to get them powder coated so the hole had to be plugged. We burned the epoxy out and then used my soda blaster to clean the remaining epoxy off. I heated the area up with a propane torch. I had the amperage set to 150A, the frequency was set to the highest frequency for a PP256, and the AC balance was set to about 65%. I was using a 3/32" 2% thoriated tungsten and a gas lense. At first the arc was erratic until I finally got a little of it to pool and got some filler rod to flow. Then I brought the filler all the way around the hole and slowly worked towards the center. The more filler I got the better the arc got. After I got the hole closed I hit it with all 150 amps and reflowed the pool. It came out pretty good. In retrospect I think the 3/32" rod was too small for 150 amps since the end balled up towards the end. I think welding tips and tricks.com helped quite a bit but does anyone here have some additional tips? I think there will be more cast aluminum repairs in my future!