Aluminum welding to repair an exhaust flange on a 36hp VW head.

[@AndyH-13]

Enjoyed watching and looks great. I wouldn’t have thought of taking out the side of threaded section of the hole. But understand this must be to get the weld to the bottom of the damaged hole.

[@johnhunt6992]

In the process of doing this to a pair of 1966 1300 heads. I've competed the welding. Cut the area out similar to yours. Heads were chemically cleaned but still had a heavy oxide layer to remove on the surface. I rarely tig weld castings, always surprised at the contamination that Can come to the surface that's freshly cut with a carbide burr and cleaned with acetone. I used 4047 10% silicone filler. I haven't set them up in the mill yet to do the machining . No cracks in my heads but exhaust guides are flogged out. I think they are untouched from the factory - car was last registered in 1987. I'm building a 1510cc engine with some NOS Kolbenshmitt 83.5mm 0.5mm oversize pistons, ported heads and a baby cam as a vintage performance engine. Also trying repair rather than throw away parts you can't buy any more. Thanks for your videos, John.

[@vwwerks]

Awesome! I'll have to look into that 4047. I know some people use 5051 and other say it can be brittle so I've always stayed with the 4043. It seems like all I have been doing lately is castings. I think it's fun to try and sculpt them back to original looking. These are pretty rough so I didn't get too carried away.

[@johnhunt6992]

Both 4043 and 4047 are mentioned in the Berg tech articles. 4043 with 5% silicon should give a more ductile deposit for say thinner areas like a port wall. The 10% silicon of 4047 gives better machineability for tapping a thread or surface milling like a gasket face - higher strength but less flexible. If you are building up an area you could use both rods as you progress, matching the specific characteristics of the filler to each area.