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Chevy 350 bored .030 Machine shop messed up

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Chevycamaro67

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Discussion starter · #1 · (Edited)
The machine shop messed up. Likely misadjusting the machine during boring, causing damage to the top of a cylinder bore. The engine block was bored .030 over and decked at the shop. Are the damages something that can be fixed or is the engine block scrap? My concern is that it may not be possible to install the pistons without damaging the piston rings, especially if the piston needs to be removed later. Unfortunately, I noticed this when unloading the engine block from my car after picking it up, so I couldn't confront the staff directly on site.
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#2 ·
More may chime in, but I don't see that as an issue. The rings are below that. When the piston is
installed use one of the ring compressors that wrap all the way around them. This way they will be
installed below that place.

Mikey
 
#4 ·
someone got carried away chamfering the top of the bore, it is standard practice to chamfer the top of the bore to ease piston/ring installation but that is about double what is normally done. it is usually .025-.030 wide.
 
#6 ·
Chamfer is too wide but chamfering top of the bore is normal. Without chamfer it would be very difficult to install pistons and not damaging piston rings.
 
#7 ·
KRUNK !!!! said:
I dont think you will have a problem with that.....Did you have just a standard .030 bore on all cyls? I never do that...I always bore each cylinder to each piston...........:)
Click to expand...
And I guess my machinist also does that. I first buy pistons, then take them and the block (and other parts for machining) to my machinist and have him machine as needed, as well as balancing, head work, etc. Then I bring it all home and do all fitting and assembly work. I trust my machinist to the max, and have NEVER had an issue with his work.
 
#8 ·
KRUNK !!!! said:
I dont think you will have a problem with that.....Did you have just a standard .030 bore on all cyls? I never do that...I always bore each cylinder to each piston...........:)
Click to expand...
It looks like boring but no honing was done. Maybe that was intentional.

It should (I hope!) be possible to take a set of .030 pistons and see which ones fit the best in each bore, then hone as required. If some are bored too big, additional .030 pistons may need to be purchased.
 
Discussion starter · #9 ·
KRUNK !!!! said:
I dont think you will have a problem with that.....Did you have just a standard .030 bore on all cyls? I never do that...I always bore each cylinder to each piston...........:)
Click to expand...
Okey. It feels good to hear that you think it's possible to use it anyway.

It's my first engine build, I suppose I'll have to learn from my mistakes the hard way...

Would you recommend doing something about the damage at the top of the cylinders? If so, what? There are quite sharp grooves in the top of the cylinder right now.

Yes, exactly. All bores are bored 0.030 over. The engine won't be any special power monster. The idea was to install hypereutectic pistons and slightly stronger steel rods along with a pair of double hump heads. But im already losing spark to continue the project when the block got damaged and I realizing things should have been done different.
 
#10 ·
Chevycamaro67 said:
Okey. It feels good to hear that you think it's possible to use it anyway.

It's my first engine build, I suppose I'll have to learn from my mistakes the hard way...

Would you recommend doing something about the damage at the top of the cylinders? If so, what? There are quite sharp grooves in the top of the cylinder right now.

Yes, exactly. All bores are bored 0.030 over. The engine won't be any special power monster. The idea was to install hypereutectic pistons and slightly stronger steel rods along with a pair of double hump heads. But im already losing spark to continue the project when the block got damaged and I realizing things should have been done different.
Click to expand...
The block IS NOT damaged. The chamfer at the the top is a bit excessive, but not problematic. When you hone the bores and fit the pistons, some of that will go away, especially the burrs at the edge of the chamfer.

Identify which piston fits best in each cylinder. Mark accordingly. Hone each bore to a good fit for the piston. Then assemble it.
 
#11 · (Edited)
I don't see any chamfer on the other cylinders maybe it's just the photo but if there isn't any chamfer then as mentioned it's hard to assemble the pistons in the cylinders & you run the risk of breaking a ring.As far as the one cylinder like others it wouldn't concern me.It also doesn't look as if it has a proper honing finish but again maybe just the photo.
 
#12 ·
I too do not see an issue here that will be a problem. As others have stated I also do not see a honing pattern, was the machine shop going to do the honing or were you going to do it back at your place? Once honed properly you will have a good block to build. :)
 
#15 ·
I would lay your head gasket on there located with the dowel pins and make sure the fire ring doesn't hang over the edge of the chamfer and also you don't want any razor thin edges that can possibly heat up and cause detonation or pre ignition. I would just lightly touch it with a chamfering cone or a sand paper drum but very lightly just enough to remove sharp edges. The two shiny gouge looking areas that shadetree55 circled are a bit alarming if they are deep.
 
#17 ·
Maybe your machine shop 'broke in' a new employee on YOUR block?? I'd definitely take it back to the shop to correct the problems. Was the block all you took them? Did you order your pistons thru that shop? If not, take them the pistons to check also for fitting.
 
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