Engine porosity

What did GM use to fix cylinder porosity. I just finished a tear down on a
5.7 truck engine. In the #3 cylinder there is a spot avout the size of a
pencil eraser. It has been filled in with something. I dug it out and it
seems to be something like JB Weld. I decided it wasn't a block that I
would use since it would need to go about .040 overbore to be useable. I
sandblasted about 15 minuites and finally got all the filler out. It is
obviously a void, not really porosity but just a casting defect. I know the
engine has never been down, I personally know the man who bought the truck
new and wore it out. Its clear that whatever was used works. The engine was
at 187XXX miles and the filler wore just like the rest of the cyl. What do
they use, where can I buy some/

"David Johnson" wrote in message

> What did GM use to fix cylinder porosity. I just finished a tear down on a
> 5.7 truck engine. In the #3 cylinder there is a spot avout the size of a
> pencil eraser. It has been filled in with something. I dug it out and it
> seems to be something like JB Weld. I decided it wasn't a block that I
> would use since it would need to go about .040 overbore to be useable. I
> sandblasted about 15 minuites and finally got all the filler out. It is
> obviously a void, not really porosity but just a casting defect. I know
the
> engine has never been down, I personally know the man who bought the truck
> new and wore it out. Its clear that whatever was used works. The engine
was
> at 187XXX miles and the filler wore just like the rest of the cyl. What do
> they use, where can I buy some/
>

I don't know what GM uses, but Cummins uses a Devcon (brand) putty to fill
porosity and voids in their cast iron blocks.

Dave