Fill rod and technique recommendations for cast aluminum

[HackAsaw]

head found on a brit bike circa 1970.

The same for Italian case engine cases circa 1975.


The same for 40's vintage HD cast cases........ talk about porous!


Thanks in advance for any suggestions you have to offer.

[chip hayden]

metallaurgically, not much of a difference in using the two most popular al. fillers 4043 or 5356.
porosity is the nature of al. castings. large, coarse grains [cystals] form when it solidifies in mold. no outside pressure to compact them doesn't help either but, that's one reason they are so light.
what you can do to minimize this is to butter and lightly peen to compact the filler into the parent metal. your cap should be less porous.

[Jerry]

Like Chip says 4043 or 5356, yet it is recomended to use 4043 on castings and 5356 for structural aluminum. Yet I have used both in trying to get a better weld. First I clean with solvent or I wire wheel castings and then heat entire casting to a few hundred degrees or so. If first weld is quite porous , I'll wire wheel the black off or even cut out weld and go at it again. At times on a porous aluminum it will take two attempts to get a good weld for the first may just burn out the impurities in the base metal, then the second pass will or should cover much better.

Good luck

[HackAsaw]

well, I should have clairified the wop castings appear to be die cast whereas the others are certainly sand cast

Not trying to trick anyone, especially myself , does this make any difference?

[chip hayden]

my experience has been that it dosn't make much difference[although i think it should].
my opinion is that a majority of al. die cast products are really more zinc than al.[zamac], excluding the marine industry[outboards and outdrives].
I've even gta welded with Alladin rod on some excessively "porous aluminum". Sometimes the poured metal doesn't weld well no matter what you do.