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I just had my 5.3l block bored .030 over and had the head surface decked, while in the process of prepping the block I noticed that there were what looked like scratches in both the front and rear main saddles. When I checked again It turned out to be some gouges in the metal, almost like it was dented. I have no idea what could have caused this, when I called the machine shop the guy told me that he had seen it before and it was nothing to worry about. Right now I don't know if I should believe him or not, asking for advice on how to address the issue.
If I had to guess, it probably happened at the machine shop. Most boring and honing units have a steel bar than goes through the main bores to locate and secure the block in the machine. The bar shouldn’t make marks like that, but it probably won’t hurt anything as long as the bores are dimensionally within spec.
Looks to me like it will leak oil somewhat out the front. Not much, but some.
Which actually might not be a bad thing... it will lube the timing chain. Kinda like the various things we all used to do up around the cam bearing for that purpose, on the old SBC.
Just make sure it doesn't have burrs thrown up around it. If there are any, file them down with a swiss pattern file, like a half-round or oval profile.
If I had to guess, it probably happened at the machine shop. Most boring and honing units have a steel bar than goes through the main bores to locate and secure the block in the machine. The bar shouldn’t make marks like that, but it probably won’t hurt anything as long as the bores are dimensionally within spec.
Agree. As if they clamped it down way to hard.
Saw those marks on both of my alum blocks after boring/honing. But they were just witness marks. Not dents. And aluminum is much softer.
I think it will be ok if there is no raised edge. Personally, I’d ask them to do a light line hone on the mains.
Thanks for the input, I'm going to see if I can't have it line bored to get rid of any burrs. My only question would be that since its going across the main journal would it have a significant drop in oil pressure?
No, not significant. It looks only acoupla .001"s deep at most. Probably will result in less than 2% increase in total oil flow through the system... IOW, negligible. As said, it will merely squirt a fine mist of oil on the crank sprocket, which will inevitably end up on the chain, which is probably good.
I'd run it as-is, as long as there's no burrs; and even if there are, I'd run it anyway after cleaning them up, as already said.
03-19-2020, 03:00 AM
Unknown damage to main 
