I had bought a 2003 6.0 out of a GMC van off of ebay and the guy had said it had a bad ratle. well when I got it in today I took of the heads and the #2 piston is shot. It has scratched the cylinder wall in a few places but not real deep. When I run my finger nail across it doesn't catch but you can feel the grooves. Just wondering if a .030 over bore will take care of this or do you think it needs to go biger?

 

run the bare block by a machine shop, let them mic the block and check out the scared wall of the cylinder, you may need to go only O10 to have a smooth wall.

but now you have an option with a damaged cylinder, turn it in to a over sized 6.0 or punch it out and make a 408.

 

For a 408 do you have to bore it, or just stroke it? Iknow you have to stroke it, but thought it was factory bore.

 

Factory Bore/4.000" Crank = 402ci
4.030" Bore/4.000" Crank = 408ci

 

Good info!!!