OK, so most cylinder heads are 355 t6. If you weld them with 4043 it machines like crap. And is soft. Some guys use 5356. It machines well I am told.
One other guy said he welded alum without using ac and did not use either of these rods. He did a bunch of stuff for BAE, so must have come up with something.
I also do some welding on 6061 T6. Same thing. I want good machineability. Suggestions?