12V engine block cylinder markings
 

I am getting ready to send of my 1996 12V block to the machine shop. When I removed the oil filter housing and oil cooler I noticed cylinders #1 and #2 look like someone took a chisel to them. Will this cause any issues? I'm looking to make around 400HP (to start)
Attachment 30590

Attachment 30591

i wouldn't be to happy about that, if your going to keep the block id take down the chisel marks and smooth them out. get rid of any sharp edges and what not to reduce the chances of cracks

I was going to do that at the very least, I just don't know if I should trust it after that. Anyone know how thick the cylinder walls are?

Knowing the thickness of the walls isn't going to help answer your question because you don't know how thick the walls need to be to make 400hp. Your machinist should have tools that can check wall thicknesses and should be able to advise you as to whether or not the block is suitable for your needs. I would smooth them out as well.

I talked to my machinist and he said those marks were from someone who tried to remove some casting flashing and got carried away and hit the cylinders. He said they would not cause an issue. And the cylinder walls are over .250" thick.