Ed Huntress wrote:
Generally they are 319 or 356 alloys, with some "fine tuning" for the
casting process in use. That's good stuff and good for casting by any
method -- particularly the 356.

I grab complete engines, rims, scrap pistons, rods and the like. Sort
them per claimed alloys then melt and ingot them.

I know that the melting changes the alloy some but for 99% of what I
cast they are close enough..

Sure. The big cast pieces, including the block and head(s), are really
good for sand casting or (in the case of 356) for plaster casting. I
don't know about 319 for plaster casting. It's probably Ok. Either one
can be cast in metal molds, too. 356 can tolerate fairly slow cooling
without dendrite enlargement, which can make them brittle. It would be
a good choice for casting in Petrobond, too, for the same reason.

Cast pistons typically are a high-silicon, low-thermal-expansion
alloy. They're really made for diecasting but they're pretty forgiving
(except to your cutting tools). You should be able to sand cast them
just fine.

I don't know about the other stuff. Little bits, like hose fittings
and the like, also are high-silicon -- often hypereutectic. They're
generally easy to cast. Structural parts may be 6061. You can cast
6061, although it's really designed as a wrought alloy.


I use the oddball stuff for items where the strength isn't a real issue,
Decorative stuff or covers and such.
The high silicon gets used for wear related items. I like using it for
castings that will end up handling abrasive abuse or in locations where
it will be the wear surface. Yes it can be a real PIA to machine but it
wears real well once finished.

It makes REALLY nice bullet molds.

I use various molds, sand, metal, lost wax/plaster. Two home built
furnaces. One is electric and one gas. The electric is NICE for temp
control and even heating. The gas is much faster to full heat but hard
on alloys.

--
Steve W.