sdlomi2

"Jim Warman" <mechanic@telusplanet.net> wrote in message
news:ftsFf.171379$6K2.159888@edtnps90...
> 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
> looks OK.
>
> 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.
I agree, Jim, a job well done. Entertaining and enlightening--much
better than reading flames so often thrown out. s