Blake, There is a difference in the aluminum used on a 1969 head and a later head, likely the difference in metallurgy. Characteristics of aluminum metal of crank cases between the years is even more evident. I have a welder who can weld .005 sheeting into cigarette diameter tubing, no matter whether it's aluminum steel or stainless sheeting. He knows the properties and characteristics of metals when subjected to the heat involved with welding, i.e., melting metal. He told me when he welded the fins, the metal was a bit more dense, tighter molecular structure, less contaminats, in later metal fins than earlier fins, the earlier fins melted more quickly and the aluminum flowed rapidly, compared to the later aluminum. As i recall, i used the fins off a 1974 head. That's why it's important to find a competent welder as the earlier and later metals react differently to heat when melted. There has to be good welders in your area. A good motorcycle shop should know of skilled welders and machinists. After you find a welder, i would explain what you have and what you need done and listen to what experience he says he has. If he has examples of his work for you to see, that would be good. I had repaired a set of unstamped s.c. cases, they were very badly damaged, two new pieces had to be machined with compound angles then fitted into the hole. The new aluminum billet was a handful to weld into the old alum. sandcast cases, but after repair, cannot see where repair line was. Of course there is significant dressing down that needs be done so one cannot see the repair. The important thing is to not rush with the project. Time taken is time well spent and your finished product will reflect your effort.
Blake, you'll have to forgive me, but being 57, i've begun noticing everyone is starting to look younger and younger (especially Allan Landry....!) Are you the "young" fellow with glasses that introduced yourself to me at the meet as our "newest member?"
