I'd be interested in seeing what kind of cast iron we could "knock off" an
engine block during water pump replacement.....
Anyway.... "back in the day" before thin wall casting, it wasn't unheard of
to see a block or manifold that had been welded. The 265 Chev (which grew up
to be the 350) was prety much the first production thin wall block... we saw
less and less in the way of welding on these since they are a bit more
delicate to work with than their progenitors. I must say that none of this
type of welding was ever done to attach one piece of cast to another.... it
was done to repair stress cracks and similar problems.
The requirements are very simple indeed.... We start with a clean block and
"nasty bit".... this doesn't stop at free of rust and dirt since cast iron
is porous... we'll need to be sure to clean it well to avoid any inclusions.
Once we have the metal prepped, we'll need to decide how to grind the pieces
to ensure adequate penetration..... without beveling, our weld will be like
beauty - only skin deep.
Next, we take our handy dandy "rosebud" torch tip and heat everyting up to
about 500 or so degrees F.... IIRC, you can take it right up to a lttle over
1000 degrees, but I wouldn't go any hotter..... You can get one of your
buddies to maintain the parts at this temp while you are welding it.... you
don't want it cooling off during the welding process.
Of course, we had to leave the parent metal and the nasty bit quite thick to
ensure proper alignment so we'll need a pretty hefty DC welder (an AC buzz
box just wont do).... something that can deliver about 300 amps or so should
be good. Then, we can take a high nickel electrode from a new, unopened
package or one that has been properly stored (if the flux gets any moisture
in it, it will fingernail from the heat of welding and wont shield the weld
adequately..... the weld will be brittle or weak and contain inclusions).
It wont be long after we get the rod into the stinger that we realize
there's a bit more to this welding thing than poking in the general area or
our desires and the welder makes it look easy because he does this sort of
stuff day in and day out....
So... eventually, we get this nasty bit joined back onto the parent piece
with what appears to be a large wad of used chewing gum...... we grind it
all down nice and use a die grinder to hog out all the inclusions we can
see. We can reduce the amperage on our welder, select a thinner electrode,
have our bud reheat the metal to 500 or so degrees F, and cap the
inclusions....... the bubble gum doesn't look quite so bad this time and
it's easier to grind the stuff off and it even almost nearly just about
After we pack up the welder and the oxy-acetylene rig and pull the roof off
a few brews congratulating ourselves on a job well done, things may be cool
enough to reassemble. We get to the bolt closest to the "ex-nasty bit" and
torque it to spec..... but, wait..... did I hear a little "POP" noise???
Hmmmm, better back this bolt out and take a peak.......
SOB..... our "ex-nasty bit" has turned into a new nasty bit. We pick it up
off the floor and notice that our weld is good since the new nasty bit broke
off right beside the weld...
About that time, we stroll nonchalantly into the house and look in the
yellow pages under "auto salvage" to find a good engine core.
Disclaimer.... the preceding piece was written to entertain, amuse and
inform..... no derision was intended.