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And now another unwanted surprise!

Dusty Dude

Local time
4:23 AM
Feb 13, 2023
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Hello All,
While doing the final cleaning of my 383 +.060 block today I discoverer this. I did not see this while doing the clearance grinding required to clear the rod bolts for the 496" stroker kit. My guess is that the fractured piece was dislodged when hit with compressed air during the cleaning. My question is has anyone had this happen and if so how did you handle it. I've got almost a grand invested in this numbers matching block and it would be a real set back if now it is not usable. I'm thinking I could grind it out but it gives me some concern about loosing a bit of piston skirt support. Thoughts please.
Dusty Dude

Cylinder pic 1.jpg

Cylinder pic 2.jpg
Was probably a void that was opened up (or made real thin) boring & honing to 0.060" OS. Grinding the rod bolt clearance opened up a side, and the air just likely blew what was left of the cylinder void away. If you have slipper skirt pistons, they likely won't go down that far, but if the pistons do, I see 4 choices:

1) Run it as is
2) Chamfer the edges of the void so they won't scratch the piston
3) Install sleeve, bore & hone sleeve to size, recut the rod bolt notch. Check the cylinders on either side as they will have been pushed in a smidge due to the sleeve interference fit
4) Start all over with another block
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Numbers matching remains possible with a sleeve at the very least.

Honestly, you should have set aside the numbers matching engine and grabbed something else if you wanted to build a stroker anyway... I know, i know, not everyone thinks that way, but my 2 cents for what it's worth.
Pricey as it will be, IMHO a sleeve is best option.. you don't know whether that pointed portion will become a crack from the expansion and contraction of the cylinder and start spreading.. It would suck in a year or so to start seeing milky oil..
I'd grind it out to the point of that crack at least. It WILL move with temperature change, likely a problem if it's not checked at least. The crack is there, you have nothing to lose by grinding it to the end.
I like the idea of installing a sleeve, but the bore needs to be further enlarged to get the sleeve installed. You might need to check with your machine shop about some potential issues doing this.

Does the void go into the water jacket? If not and it is solid overall without a crack that is spreading, it may not matter too much. Sometimes the best idea is to not do too much. Think about it, you just notched the bore for clearance anyway. Simply enlarging that notch may be the way to go...
Just dress it out with the stone you used to make the notch in the first place. dont over think it
Thank you all for your replies. After looking at it and consulting with my machinist I'm just going to dress it up and get rid of any sharp edges and blunt the pointed end so it won't propagate a crack and let her rip. Machinist says this is really pretty common and has had them show up all over the place. As long as they aren't in the ring travel area don't worry about it. Thanks again everyone.
I agree that If the rings stop well above the suspect area just dress it and run it…. Probably not very much skirt on the 496 cu pistons anyway….

it actually looks to me like it has been that way for quite a while and not a fresh break…

496 will be fun for you! Enjoy