Dvst8r asked to post up some pics of my oxy-acetylene aluminum welding, so here you guys go...
This is a really big hole that needed to be plugged. It was where the EGR piping (which is now cut off and ground away) entered into the plenum. I opened it up until the wall thickness around the hole was uniform and made a "keystone" shaped cross-section so I could make a plug that fit securely without falling through:
Here is the plug fabricated out of 1/4" 6061 (and the tighter the fit-up, the better):
The area pictured above just welded (flux resides also washed off with hot water and soap):
... and now after grinding the beads down flush we can see how good the fusion really is. What a successful weld will look like here is uniform metal. This looks pretty good, but there is one area in the upper-right of the weld bead where a telltale thin line of non-shiny oxides shows that the molten metal didn't flow together correctly:
There are a couple little holes (originally brake booster vacuum line and valve cover crankcase vent return lines on the gasser application) that I wanted to plug so I started by fabricating tight fitting plugs and hammering them snugly in:
then, the view after welding:
And after being ground down:
The weld beads on both of these plugs had perfect fusion all the way around on both!
I think the reason they came out so well was I had my flame set very hot when doing them.
But another area I tried welding (an attempt at repairing a previously botched weld) didn't come out quite so well. I didn't use enough heat so didn't get good fusion. I might have to try re-welding it... again. :roll:
Previous botched weld ground out ready for repair attempt:
After welding repair attempt - before cleaning off flux and oxide residue:
After cleaning off flux (just soap and water):
And after being ground down flush. Yikes, this doesn't look much better than it started. The metal has many areas that didn't get fused together. This is because I didn't use a hot enough flame.
This has been good practice, so I feel more prepared for taking on the more challenging aluminum welding jobs needed elsewhere on the manifold.