Richard wrote:
On 3/19/2012 7:28 PM, Ed Huntress wrote:
On Tue, 20 Mar 2012 00:23:24 +0000, David Billington
wrote:

Steve W. wrote:
Bob Engelhardt wrote:
There were 2 heads at the dump, each for 2 cylinders - from a a v4
engine I'd guess. Each of the heads had 1 cylinder badly "burned",
as shown. Anybody know what happened?

Just curious,
Bob

http://home.comcast.net/~bobengelhardt/EngineHead.jpg
Looks like timing belt/chain failure. That stuck 2 valves out in each
cylinder for the piston to hit. These break off then rattle around in
the cylinder and beat the crap out of everything. This is the end
result. You DID pick up those heads didn't you??? They are GREAT to
cut up, melt down and use for casting your own projects.

Typically they would be. A mate that works in engine development has
mentioned that the heads are invariably cast from virgin aluminium in
order to guarantee the material behaves as required, at least the major
players.
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'm curious what it takes to do that.
I've cast lead for ballast with nothing more than a propane torch,
albeit a big one.

What does it take to cast aluminum?
Beyond the obvious heat, what are the dangers?


LOT's of controlled heat. I use propane for one furnace and electric for
another. Each has Pros/Cons.

The BIG pro with the electric is that you can ramp the heat down VERY
slowly to control problem alloys.

Danger wise it is similar to lead, HOT metal that can start fires if it
hits flammable materials. I have a 4" DRY sand layer over the concrete
floor in the casting area. Molds can be more precise IF you know the
metals shrinkage rates.

Personal protective gear needs to be better because of the higher temps.

It is real nice though to have as a skill since with it many
"unrepairable" castings become repairable. I have taken damaged
castings, built up damaged/worn areas with bondo, sprayed them with
spray-fil to compensate for shrinkage, then used them to create a mold
and cast a new part. Have a couple garden pulling tractors around with
"factory" carbs that have subtle work done in the bores and passages to
increase flow that look totally stock down to the casting numbers....
Or how about a casting that keeps failing due to poor design or extra
stress. You can make a mold, add stiffening fillets, embed steel rods,
add material or whatever else you need. On one of our fire engines the
water drain manifold was a crappy design with a bunch of plain steel
fittings cobbled together and lines running everywhere along. I cast up
a new one out of alloy that has PEX style hose connections, single
outlet with molded in mounting ears and a much more dependable valve
control.

--
Steve W.