Machine shop imperfections
 

I just picked up my block from the machine shop a few days ago and on closer inspection I saw this imperfection in the bore. I plan on taking it back to the machine shop Wednesday to show them but wanted some input from you guys first.https://cimg7.ibsrv.net/gimg/www.mia...f4784cea78.jpg
It's in cylinder number 3 and I havent done anything to the block since picking it up. One problem they did mention was that the 2nd ring clearance was .001 to .002 over which I've read isn't too big of a deal but the shop said they came that way and wanted to double check and see if that was a common occurance. Here's some more info on the work I had done and the parts I'm using.
Block cleaned, line bored, 84mm cylinder bore, decked
Had them do all the bearing clearances, pistons, rings gaps, rotating assembly balanced, the whole works
I'm using 84mm 9.0:1 supertech pistons with wiseco rings.

In my head I paid for a perfectly bored block and didnt receive what I paid for, so I'm already thinking this isnt meeting the standards for my build. And i am worried the rings could get snagged on it during installation or it cause them to not seal properly, or worse. I can just feel the the groove with my finger and my fingernail can slightly catch it if I drag over it.
Let me know what you guys think! Thanks

My machine shop would buy me a block.

I'd be mightily pissed if that were my engine.

On the one hand, it looks to be above the area that the upper ring will sweep while in operation.

On the other hand, piston to bore contact is a thing that happens.

If it were my engine, I'd install the crankshaft along with the piston (minus rings) and rod in that cylinder, and see if the piston crown reaches that level at TDC. If it does, then the shop owes you a new block.

I've gone from pissed to irate now. So I stopped by the machine shop with a picture and talked to the guy who did the work and he said he never noticed the mark before and wants to see the block to see if it could be used. I went back to the block to take some more pictures and measurements when I saw the cylinder wasnt sharp on the side of the mistake and you can visually see the sanding marks where they tried to cover this up. You can easily see how sharp cylinder number 4 is and how rounded number 3 is in comparison https://cimg2.ibsrv.net/gimg/www.mia...d61d6fb771.jpg
https://cimg5.ibsrv.net/gimg/www.mia...63c7b01279.jpg
https://cimg7.ibsrv.net/gimg/www.mia...147d61a6b3.jpg

Yeah, your machinist really sucks.
I personally would not use that block, even though it looks to be high up enough that it miiight not touch, but I'd still not risk it.

another concern would be: if he's shady enough to try to cover up such a big mistake, who knows what other mistakes he made. might want to re-measure all the specs if you do decide to reuse it

That's a big fat hail naw. They owe you a virgin block and your money back so you can take said virgin block somewhere else.

LOL, you can see the ring he/she wore around the top surface, from trying to hide that f up.

Youre in NASCAR central, how did you find a shop with such quality work!?

I don't know how you'd win this argument. He'll likely say it was that way when he got it... he said, she said.

If your topring does not go that high (assume the top of the piston is even with the deck), then that will never be an issue. If you are worried about damaging the rings during installation, you could put a tiny amount of superglue (or something) to fill it, sand it and then it'll burn up upon use.

Also, NEVER trust the shop. I have been through 4 shops in the past year and measure, measure and measure again if you insist on having it right.

I'm less concerned about the groove itself than I am the damage they caused trying to hide it. The corner of the top of the bore looks really rounded off and head gasket sealing is a thing, so....

Someone bumped a hand wheel when the mill was running with the tool inside the bore. Never drop a quill until your X and Y are locked. Machine shop 101.

Cuious what machine shop you used. You got a PM, I have a local shop I have been happy with. Will be dropping off a block to them later today for some work.

I defnitely would not run it

In most racing-aerospace machining & maintenance industries, making a mistake is a forgivable act.

Trying to cover up a mistake is a firing offense.

They owe you an apology and a new block.

Oh hell no.

Yep, I agree. That's a big fuck no.

The crap on the top deck surface around the bore. I would personally probably send it they decked it again and the top ring didn't hit that groove, but not on something i super duper cared about, and only if they gave me all my money back.

I'm reading lots of negative comments, but not one clear explanation for why it is a problem. Can someone clear up the question of, why?
(not trying to be argumentative, just want to learn from this)

If the groove at the top of the cylinder is the only issue, then the block is usable.

The concern here is that the shop obviously did a half-assed job of trying to remove the evidence, and didn't tell the customer about the faux pas. That begs the question as to what else in the machining process might have also been fucked up. It's a mark not merely of bad workmanship, but also of dishonesty, the latter of which is far more concerning.


In my job as the director of engineering of a large television station, I see lots of damaged equipment. Cameras and microphones in the field get the shit beaten out of them routinely. It's just a fact of life, and we budget for it.

A good photog will come back to the station with a camera that fell off the tripod and then got run over by a fire truck, and say "I didn't lock this camera down, and it fell off the tripod and then got run over by a fire truck." And I'm fine with that. Yes, it was a $25,000 camera and lens combination, and yes, I wish you'd checked the lock on the tripod before you walked away from it, but I understand that crazy shit happens when you're at the scene of a train derailment at 5am, in the rain. Thanks for letting me know, I'll call the assignment desk and let them know to re-equip the crew that was going to use it next.

A shitty photog will come back to the station and stick the camera bag back on the shelf without saying a word about it, so we don't find out until the next crew comes on shift, goes to grab their camera out of the equipment room, and finds that it's trashed. At that point, not only do I have a trashed camera, I also have a crew sitting around with no gear who are unable to cover their assignment.



The machine shop, in this case, is the shitty photog.

I would take it to a different machine shop and explain your concerns and get a professional opinion. I would also have them measure everything to check the other shop's work even though it will cost money. If they find that the damage is beyond the scope of usable they could easily resleeve that one cylinder and make it better than new. Sleeves are stronger and have a more consistent wall thickness than the cast block originally comes with.

I would not deal with the original machine shop except to relay the findings of the second shop and ask for compensation for some of the rework. You will likely get nothing or nearly nothing out of them because they've already demonstrated their character.