I have a cast aluminum camshaft holder from a motorcycle that had an ear on it snap off. The ear holds the rod for the tachometer output, there's a worm gear at one end that meshes with a gear on the cam that spins the rod to register the engine RPMs. It cracked off pretty cleanly, so I just cleaned it up and TIG welded it back up last night; I'm happy with the outside, other than a couple of boogers, but I didn't get penetration all the way through (well, I actually did on one side, but it didn't fuse). I can't really come at it from the other side, it would require so much stickout that I wouldn't have any gas coverage. It feels solid, I banged it on the edge of the table a couple of times and it still held. Is there more that I can/should do? The camshaft holder will be bolted firmly to the head, the ear just floats, so I don't think it will be subject to a lot of stress. This is ~1/8" thickness.
Here's what I ended up with. One of these is blurry and looks like it's got some undercut, but the original casting is rounded right there and I didn't need to go far enough to cover it up. On the last picture you can see the remains of the crack on the inside.
Here's what I ended up with. One of these is blurry and looks like it's got some undercut, but the original casting is rounded right there and I didn't need to go far enough to cover it up. On the last picture you can see the remains of the crack on the inside.